Design for manufacturing & assembly report (table lamp)

0303.801.01 | Design for Manufacture

Joshi – Khamkar – Vasquez

Project Report

N4

Joshi | Khamkar | Vasquez

DESK LAMP

DFM | DFA Analysis



Table of Contents

Introduction.......................................................................................................................................3

Project Description.............................................................................................................................3

Parts and Subassemblies.....................................................................................................................4

Project Plan........................................................................................................................................7

Solidworks CAD Models......................................................................................................................1

Exploded view Drawings and Animation.............................................................................................5

DFM analysis of the selected parts…………………………………………………………………………………………….. 0

Part analysis and Redesign ideas……………………………………………………………………………………………….55

DFM Cost analysis……………………………………………………………………………………………………………………78

Appendix............................................................................................................................................6

1



Introduction

Design for manufacturing and design of assembly is the art of bringing together product design

and product planning in single activity to achieve the goal of ease of manufacturing, reliable and cost

effective product. The aims of applying DFM and DFA to a product are:

1. To design a product on the basis of ease of manufacturing.

2. To select manufacturing processes which are simplest, economical and have least manufacturing

time.

3. To reduce the total number of parts as this is the most effective method to bring the costs down as

well as it reduces the intensity of all activities related to product during its entire life.

4. To maximize the use of standard components because of their ease of availability and reduction in

lead time.

5. To avoid use of separate fasteners as they increase the cost of manufacturing due to handling and

feeding operations that have to be performed.

6. To decrease the manufacturing and assembly costs and at the same time improving the quality and

reliability of product.

Project Description

The product that we have chosen for our project

is a Desk lamp. It consists of metal base to which a

bracket is fixed. The bracket is made of steel and contains

number of linkages and springs attached to it which

govern the movement of lamp in the x-y direction. There

are three springs used in the overall assembly allowing

for the adjustment of lamp top to the adequate position.

There is a top of the lamp which is made of steel and is

used to reflect light in a specific direction. There are two

arms of product, the lower arm has three links/ struts

each combining with one the springs, the middle link and

spring combination allows the movement of upper arm

and other two links and spring combination allows for the

2

Desk Lamp 2013 By Pedro Galiano - Grabcad

http://grabcad.com/pedro.galiano-1



movement of the lower arm. There are two screws which attaches the lower arm to the bracket.

Fastener is used to make a connection between middle spring and link. There are two more fasteners

which are used to make connection between upper and lower arm and also between lamp top and

upper arm.

Parts and Subassemblies

Total number of parts: 21 Total number of sub-assemblies: 4

Part No.

Name Reference Image Description Manufacturing Process

Material Qty.

1 Base

Support to arms and shades. Usually the

electrical components are connected to it.

Forming Metal 1

2 Base Joint Supports the links and Cutting and forming Metal 1

3 Strut- LongProvides outwards-

facing support in the lengthwise direction

Extrusion Metal 2

4“Elbow”

joint - female

Assembly and structural support. Allows movement.

Casting Metal 1

3

Desk Lamp 2013 By Pedro Galiano - Grabcad

http://grabcad.com/pedro.galiano-1



5“Elbow”

joint - male


Casting Metal 1

6 Spring - Short

Traction Coiling of extruded wire

Metal 2

7 Joint-a Assembly between struts

Casting Metal 1

8 Joint-bAssembly and

structural support. Allows movement.

Casting Metal 1

9 Strut- Short Support Extrusion Metal 2

10 Joint-cAssembly and


Casting Metal 1

11 Joint-dAssembly and


Casting Metal 1

12 Head / Shade

Covers the light bulb on a lamp to disperse

the light

Forming and punching

Metal 1

13 Socket

Sub-assembly Provides electrical connections

to the bulb and supports the lighting

fixture.

Injection moldingCombination Of different

materials1

4



14Base

supportCovers the electrical

fixtures inside the basePlastic injection

molding Polymer 1

15 Spring - Long

Traction Coiling of stainless steel wire

Metal 1

16 Pivots Joint to assembly struts with the base.

Extrusion process and then required machining process

(chamfering)

Metal 3

17 Wheel To lock two parts together.

CNC machining (cutting and threading)

Metal 2

- The design of some parts could be changed. - The materials will be assigned during the DFM process. - Cord and electrical components are not included in the selected 3D model.

Assembly

5



Project Plan

The work for the three deliverables of SolidWorks, DFM and DFA has been distributed evenly amongst all the three team members. The primary contributor is selected by discussing the strengths of each team member, and then assigning others to support him/her in his task. This has two benefits,

1. The primary contributor will not be overloaded with work,

2. The primary contributor can share his/her knowledge with others assisting them in their work.

However, in some tasks due to time constraints and size of the task, even the reviewer has been assigned the task of assisting the primary contributor, while in some other cases where the work load is not very large, the person assisting can carry on with other tasks in parallel.

TaskResponsibility Due

DateK. V. H. K. A. J.

SolidWorks CAD Model

Analyze the CAD model in SW from a design point of view

Primary Contributor Assist Review 04/08/12

Create an assembly animation that shows sequence in which parts are assembled.

Primary Contributor Assist

Cross check the parts list & keep track of changes made after

design analysis, while providing feedback

about the same.

04/12/12

DFM Analysis

Review Primary contributor Assist

Review design analysis.

Analyze 3 main components in extreme

detail for compliance with DFM guidelines.

Assist in checking the parts which do/don’t align with DFM design

guidelines.

04/23/13

Provide feedback on redesign ideas.

Redesign parts to improve their manufacturing.

Assist H. K. in redesigning. 04/24/13

Detailed dimension drawings.

Manufacturing cost using DFM costing software.

Assist H. K. in manufacturing cost

estimation.04/26/13

DFA Analysis

Assist Review Primary contributor

Assist A. J. in making Assembly plan Review Assembly analysis

Make a detailed assembly plan, with

help of drawings and animation , if required

05/03/13

Assist A. J. in analyzing the product parts, while looking for all possible improvements

Assist & review DFA analysis

Analyze all parts for compliance with DFA

guidelines05/04/13

Assist A. J. in analyzing assembly design and costs

Review and provide feedback about suggested

changes

Calculate before and after time for

assembly times and cost

05/03/13

6


Joshi – Khamkar – Vasquez Project Report – N2

0



Solidworks CAD Models

The solidworks models have been uploaded to the group locker. The parts named as not imported are the ones selected for the DFM analysis. These parts have been done again in solidworks (without changes in the form) to correct and reduce features. The ones named as Imported are the original parts. (These was uploaded on the 8th/April to the group locker and has been updated on the 12th/ April).

The parts selected to perform the DFM and DFA are:

Part No.

Name Reference Image Description Manufacturing Process

Material Qty.

2 Base Joint Supports the links and Cutting and forming Metal 1

4“Elbow”

joint - female


Casting Metal 1

14Base

supportCovers the electrical

fixtures inside the basePlastic injection

molding Polymer 1

1



The solidworks design of these parts have been improved according to good modeling practices. The original parts were modeled on other software, for this reason the feature recognition of solidworks throw unusual modeling features.

- Base_Joint_Not Imported: The part on the left was the imported version of solidworks which was not correct. The part on the right is the Not imported improved version which has less features operations.

2



- Elbow_Joint_Female_Not Imported: The part on the left was the imported version of solidworks which was not correct. The part on the right is the Not imported improved version which has less features operations.

3



- Base_Support_Not Imported: The part on the left was the imported version of solidworks which was not correct. The part on the right is the Not imported improved version which has less features operations.

4



Exploded view Drawings and Animation. These documents are available on the solidworks files on the group locker.

5



Part A:- Analysis using DFM design guidelines:-

1)Female joint:-

(Assumption:- the part is assumed to be made up of Al 6061)

a)Mass and Volume:-Mass = 19.97 grams Volume = 7395.30 cubic millimeters

b)Parting line:-

The parting line can be selected either along the X, Y or Z- axis. Selecting the X-axis (fig.1) causes formation of undercuts as shown in figure 2. This is an undesirable feature. Selecting the Y-axis as the parting line can lead to problems due to misalignment of the two holes. Since their centers are not lying on a horizontal line, it will be difficult to manufacture the mold at the intersection plane.

0



Fig.1

1



Fig.2

Fig.3 Fig.4

Manufacturing the part with the Z-axis as the parting line enables us to use symmetry in both the molds. This seems to be the most feasible (least problematic) option, we shall select the Z-axis as the parting line. As shown in the fig.3 the parting line will be positioned in the center of the two symmetric halves. However, the only problem we shall face is of flashing due to cores being passed through the parting line (to accommodate side action features explained below).

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Fig. 5The above figure shows the one half of the part, which will be manufactured in either of the molds. The holes shaded in yellow will be made using core slides.

c)Side Action:-3



Fig.1

4



Fig.2Figures 1 and 2 above show the surfaces which will be made using side action, due to undercuts. The region of the part shown in blue in the above figure will be made using side-action core slides, while the two holes will be done using core slides along the direction of the opening and closing of the mold. This may cause some flashing.

5



d) Thickness Analysis:-

Fig.1The thickness analysis above shows clearly a lot of variation in the thicknesses of various cross sections across the whole part.

Section 1:-6



Fig.2 Fig.3

Fig.4

Fig2. shows the section view, and fig.3 and fig.4 show difference in thickness values of various wall sections of the part.

Section 2:-

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Fig. 1

Fig.28



Fig.3

Fig.4Fig1. shows the section view, and fig2., fig.3 and fig.4 show difference in thickness values of various wall sections of the part.

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Fig.5The snap feature used on the part (circled in fig.5), has a gradually increasing thickness. While manufacturing this part, the non-uniformity in its thickness may cause problems related to material flow. Also, the need for accuracy of the sharp corners, of the snap fit, shall increase the cost of mold manufacturing.

Section 3:-

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Fig.1

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Fig. 2 Fig.3

Fig1. shows the section view, and fig2.shows the difference in thickness values of various wall sections of the part. Also the encircled region in fig.3 is at the point of intersection of the circular feature and semicircular feature. This region of intersection has a sharp edge formation, which makes flow of material very difficult. Along with this manufacturing this feature, will ask for added precision on either of the molds, due to the sharpness of the edge.

12



Section 4:-

Fig.1

13



Fig.2

Fig.3

14



Fig.4

Fig.5

Fig1. shows the section view, and fig2., fig.3 and fig.4 show difference in thickness values of various wall sections of the part. These three figures clearly indicate the variation in thickness values of the cross section. The length of this cross section is 35mm. And there are a couple of steps along this length, which may be difficult to manufacture, due to the long distance that the material has to travel. Also, there exists a possibility that the material may get dried up, due to low wall thickness and faster heat dissipation.

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Section 5:-

Fig.1

16



Fig.2

17



Fig.3

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Fig. 4Fig1. shows the section view, and fig2., fig.3 and fig.4 show difference in thickness values of various wall sections of the part. The encircled regions in fig.1 show the sharp decrease in cross sectional area of the part. This presents a space with very low cross-sectional strength, and will be a region of very high possibility to breakdown (crackup), due to high stresses on both sides of the part (since this part is used as a joint between two different linkage assemblies of the lamp).

19



Section 6:-

Fig.1

20



Fig.2

Fig.3

Fig.4

Fig1. shows the section view, and fig2., fig.3 and fig.4 show difference in thickness values of various wall sections of the part. These three figures clearly indicate the variation in thickness values of the cross section. The length of this cross section is 35mm. And there are a couple of steps along this length, which may be difficult to manufacture, due to the long distance that the material has to travel. Also, there exists a possibility that the material may get dried up, due to low wall thickness and faster heat dissipation.

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e)Draft Analysis :-

Fig.1

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Fig.2Fig.1 and Fig.2 shows the draft analysis of the part. The regions shown in yellow color requires a draft, while the region shaded in green, already has a sufficient draft. Both the holes require some draft, to facilitate easy removal of the core slides.

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f)Holes:-Hole 1:-

Fig.1

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Fig.2As seen in the above fig 1 and 2 the depth of the whole is less than 38mm, which is the limit for the given diameter, for an Al alloy.

25



Hole 2:-

Fig.3

26



Fig.4

As seen in the above fig3 and 4 the depth of the whole is less than 16mm, which is the limit for the given diameter, for an Al alloy.

27



Hole 3:-

Fig.5 fig.6

Fig.7

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As seen in the above figures the depth of the whole is more than 25mm, which is the limit for the given diameter, for an Al alloy. Hence the length of the hole/slot needs to be decreased.

g)Core Slides:-

Fig.1 Fig.2The region shown shaded in green, will be made by a core slide moving perpendicular to the direction of the parting line. While the two holes shown shaded in blue will be made using core slides, parallel to the direction of the parting line.

29



h)Radii and fillets:-

Fig.1

30



Fig.2The corners and edges shown shaded in blue in fig.1 and fig.2 will require fillets for ease of manufacture, and to reduce the cost of manufacturing the mold.

Fig.3

31



Fig.4The corner edges shown shaded in blue in fig.3 and fig.4 need fillets of up to 1.5 times the thickness of the wall to which they belong to. These sharp corners ask for high cost of manufacturing on the molds and are regions of high heat concentration, which may further lead to cracking as well.

2) Base Joint:-

To manufacture this part, we will have to cut a metal plate into the basic feature shape of the given part. This will be followed by drilling of holes to pass the circular rod through them. Another set of holes shall be drilled to accommodate snap fits of the features on the top of the part. After these holes are drilled, the part will be bent in a punch-die arrangement. While doing the bending operation, the change in material length shall be taken into consideration, to accommodate the bend. This accommodation shall depend on the radius of the bend, material thickness and the surface area of the part to be bent. This will be followed by passing of the rod through the parallel aligned holes, at the bottom of the part. This rod will be welded into the part geometry. After the welding has cooled down, the two small features on the top of the part, shall be snap fitted while keeping a close tab on part tolerances, to provide a tight fit.

Material:- Al 6061

Mass = 52.22 gramsVolume = 19341.93 cubic millimeters

32



1. Thickness of sheet v/s diameter of holes:-

Fig.1

33



Fig.2

Fig.3

34



For bending of alloys, the diameter of holes made in the part, should be twice the thickness of the sheet metal. The holes at the bottom of the joint fig.2 are less than 4mm in diameter and hence violate this guideline.

2. Thickness of sheet metal v/s base arc radius:-

Fig.1The minimum bend radius should be at least six times the thickness of the sheet metal. This design guideline is violated in our case, and the radius of the bend needs to be increased to 12mm atleast.

35



3. Distance between hole and adjacent wall:-

Fig.1As shown in fig.1 the distance between the hole at the base of the additional feature and the closest edge of the part is greater than the value of one thickness of the sheet metal. Hence, this design guideline is well followed.

36



4. Flange length v/s material thickness:-

Fig.1 The flange length should be greater than four times the material thickness. The flange is defined as the feature of the part, in between two bends or from one bend to the edge of the part. In either scenarios, this design guideline is not violated by our part, as shown in fig.1.

5. Length of base v/s side length:-For a U-channel the length of base should be less than or equal to the side length. In case of our part, the length of both the sides is greater than 38mm.

6. Hole alignment:- Both set of holes, at the bottom and the top of the part are aligned properly, with their centers passing through a horizontal line. This facilitates ease of manufacturing.

37



7.Distance between hole and bend:-

Fig.1The distance between a hole and the adjacent bend should be greater than 1.5 times the thickness of the sheet metal. In our case 14.5mm is greater than 4mm.

Blanking Operation:-While cutting the sheet metal into its basic profile it needs to be seen that the feature obtained does not have any sharp corners or edges, and the ends are well-rounded. This guideline is well followed in our part.

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3) Base Support:-

Material:- PS medium/high flowMass = 75.05 gramsVolume = 72167.90 cubic millimeters

1. Parting edge : Parting edge is selected such that the surface shown in green color is manufactured in one half of the mold. Taking parting edge this way eliminates any side action and also make bosses perpendicular to the parting line.

Figure1: Parting edge

2. Side action : The hole at the center will be manufactured using side action of core slides.

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3. Wall thickness: The wall thickness is constant across most of the cross section except the areas where bosses are attached, where the maximum thickness goes up to 6 mm. Thus it does not meet the design guidelines. Also the thickness of section 1 mm is less than the thickness of average section for any plastic material thus thickness needs to be increased.

Figure2: Wall thickness analysis showing thickness less than 2.50 mm

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Variation in wall thickness

Fig.3a

Fig. 3b

41



Fig.3c: Thicknesses at various cross sections ranging from 1 mm to 6 mm

4. Holes: a> Spacing between hole and nearest edge is less than 1 diameter thus, it does not meets the design guidelines.b> Hole is perpendicular to parting edge thus does not require side action.c> Depth of the hole is greater than twice the diameter of the hole.

42



Figure4: Hole diameter and distance from nearest side

5. Bosses:

Boss1:

a> Thickness of all the bosses is 2 mm at every section and it is attached to wall of thickness 1 mm but the thickness of bosses should be 40% to 60% of the thickness of the wall they are attached to thus it does not meet the design requirement.

b> Bosses should not be 2.5 to 3 times higher than the wall thickness and here they are exactly thrice the wall thickness thus it meets the design guidelines.

c> Bosses should be two wall thicknesses apart and thus it meets the design guidelines here.d> Bosses should be perpendicular to parting line thus it meets the design guidelines.e> Bosses should have draft of 0.5 to 1.5 degree but it does not have any draft here thus violates design guidelines.f> Bosses should have 25% to 40% radius at the base of the wall thickness but it does not have any radius thus it does not meet design guidelines.

43



44



Figure5: Thickness and height of bosses

Boss2:

a> Thickness of all the bosses is 2 mm at every section and it is attached to wall of thickness 1 mm but the thickness of bosses should be 40% to 60% of the thickness of the wall they are attached to thus it does not meet the design requirement.

b> Bosses should not be 2.5 to 3 times higher than the wall thickness and here it is twice the wall thickness thus it meets the design guidelines.c> Bosses should be perpendicular to parting line thus it meets the design guidelines.d> Bosses should have draft of 0.5 to 1.5 degree but it does not have any draft here thus violates design guidelines.e> Bosses should have 25% to 40% radius at the base of the wall thickness but it does not have any radius thus it does not meet design guidelines.

45



Figure6: Thickness and height of boss2

Boss3:

a> Thickness of boss is 2.39 mm at every section and it is attached to wall of thickness 1 mm but the thickness of bosses should be 40% to 60% of the thickness of the wall they are attached to thus it does not meet the design requirement.

b> Bosses should not be 2.5 to 3 times higher than the wall thickness but here it is 4 times thus does not meet the design guideline.c> Bosses should be perpendicular to parting line thus it meets the design guidelines.d> Bosses should have draft of 0.5 to 1.5 degree but it does not have any draft here thus violates design guidelines.e> Bosses should have 25% to 40% radius at the base of the wall thickness but it does not have any radius thus it does not meet design guidelines.

46




Boss4:

a> Thickness of all the bosses is 5.34 mm and it is attached to wall of thickness 1 mm but the thickness of bosses should be 40% to 60% of the thickness of the wall they are attached to thus it does not meet the design requirement.

b> Bosses should not be 2.5 to 3 times higher than the wall thickness and here they are exactly thrice the wall thickness thus it meets the design guidelines.

c> Bosses should be perpendicular to parting line thus it meets the design guidelines.d> Bosses should have draft of 0.5 to 1.5 degree but it does not have any draft here thus violates design guidelines.e> Bosses should have 25% to 40% radius at the base of the wall thickness but it does not have any radius thus it does not meet design guidelines.

47



48




49



6. Draft: There is no draft in bosses perpendicular to parting edge and thus draft is required in the area shown in yellow after draft analysis.

50



Figure9: Draft analysis

7. Corner and radii:- A slight amount of radii should be given at the base of all bosses, since sharp corners on the mold will facilitate high heat concentration points, which are not desirable.

8. Core Slides:- 51



Fig.1

A core slide will be used to manufacture the hole shown in figure 1. Due the chamfer feature on the inner side of the hole, loading and unloading of the core slide will be an easier task.

52



Part B:- Redesign of parts:-1.Redesign of the female joint:-

1.Analyses of female joint with a hollow inner side as shown in fig. A (region shaded in yellow color):-

Fig. A

53



Fig. 1

Fig. 2

54



Fig. 3

Fig. 4

55



Fig. 5 Fig.6

The female joint has a lot of thickness variations, as is visible when we take the cross sections of the part along X, Y, Z – axis (shown in fig. 1 to 6). These thickness variations can lead to the following problems:

Sharp corners and sharp edges in the part Difficulty for material flow while moving through regions with sudden steps Possibility of material drying up quicker than estimated, due to more than allowed length of material flow (as per the given design guideline

for length of a hole) Formation of sharp corners on the mold, leading to difficulties in mold manufacturing, and leading to a need for greater precision during mold

design.

56



Fig. 8

Along with the problems mentioned above, the yellow shaded region has an additional problem of having a futile slot inside itself, as shown shaded in blue in the section view above in fig. 8. In the actual assembly the positioning of this slot is not utilized to assemble or join together two entities. The only visible purpose served by this slot is of saving material (Fig.9 ).

57



Fig. 9

Also the length of the whole slot is more than what is actually required as per design guidelines for holes in Al alloys (table1).

58

The regions encircled in the figure, show portions of the female joint which are used to form joints or linkages. However the portion, which is not encircled, is not used in any way to provide any kind of linkage or joint. However, the inside of this part has a slot manufactured to save material (fig. 8), but it serves no specific purpose in the assembly of the part.



table 1

Fig.10

59



Redesign recommendations:- As seen in the above fig.10 the depth of the whole is more than 25mm, which is the limit for the given diameter, for an Al alloy. Hence the

length of the hole/slot needs to be decreased by at least 10 mm. Also, the cross section of the region shaded in fig A. at the top, can be changed from rectangular to circular ( or a solid rectangular cross-

section with reduced and uniform thickness), to reduce material thickness, save material, eliminate the inside hollow feature (shown shaded in blue in figure 8). This will also help to easily manufacture the part, by eliminating side action feature of the part, which was required earlier. However, this can be done only if the new value of reduced thickness of the cross section is appropriate to facilitate proper and faster cooling of the part.

1. Analysis of joint formed at the intersection shown in fig.1:-

Fig. 1

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Fig.2The intersection encircled in fig.1 and fig.2 will be problematic while manufacturing, with regards to the flow of material and the sharp corners required on the mold during mold manufacturing. This region provides opportunity for accumulation of heat due to improper dissipation while cooling down.

61



Fig.3The region encircled in fig. 3 shows sudden steps and critical regions with regards to material flow and the tensile strength of the part at this concerned section, due to small cross sectional thickness. Since this female joint is going to join two linkage sets of the lamp, this joint needs to be able to take all the load of the linkage weights, distributed gradually over its entire length.

Redesign recommendation:- 62



Fig.4 Fig.5

The feature shown in fig.5 can be redesigned using guideline shown in fig.4. This will definitely eliminate the intersection joint, thus making mold manufacturing much easier than earlier. Along with this the length of the hole can be reduced to accommodate the joining pin only up to the length required, rather than the entire pin. A little draft needs to be given to the hole to accommodate ease of removal of the pins.

2. Alignment of holes:-

63



Fig.1 The alignment of the two holes (smaller and bigger) can be changed such that their centers lie in a plane parallel to the horizontal plane.

This will somewhat increase the ease of machining the cores for these two holes in the molds.

3. Eliminating distance between two holes:-

64



Fig.1 Fig.2

The two wheels, shown shaded in yellow in fig.1, with holes in each of them are required to join the male joint, and thus the lower linkages, with the above linkages. Due to the presence of two wheels, it takes extra material, while adding difficulties in manufacturing, by adding undercut features when the part is manufactured along the X, Y axis, as shown in Fig.3 (shaded in green).

65



Fig.3Along with the undercut feature, it also adds the presence of the intersection with the smaller bose with hole. Due to such a geometry, the cross section has sudden changes in thickness levels as seen by taking it cross sections, shown in Fig. 4

66



Fig.4

Redesign Recommendations:- The two wheels of the female joint can be replaced with one single male joint (Fig.1). In this condition we will be able to eliminate the

undercut feature, and ease the manufacturing of the part, by removing the side action feature required for the slot to make hollow spacing inside the female joint. The feature will then have uniform thickness cross-section with no sudden steps, thus eliminating weak cross-sections in the part (as shown in fig.2)

67



Fig.1

Fig.2 (top view cross section of female joint) This redesign can be done, assuming that the two sets of linkages (upper and lower) are connected by two male joints, such that the pin

joining these two sets of joints, has sufficient tensile strength to handle the weight of the upper linkages, and torsional strength to provide ease of rotation of the lamp assembly at this joint.

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2. Redesign of the plastic base support:-

1. Positioning of the hole at the center of the base support :-

Fig.1

69



Fig.2

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Fig. 3 After analyzing the base plate assembly (consisting of base support and metal cover plate over it, we can see that the two parts are joined

together using a snap fit, since the outer diameter of the cover plate is equal to the inner diameter of the base support (as shown in fig. 2). Thus the chamfered hole shown in fig. 1 is not required, unless and until it is used to pass a core to hold the base support structure in place, while making its web structure during injection molding.

Also, to have a proper snap fit, it would be advisable to have three to four equidistant snap features on the outside of the base support plate and then place the metal cover over it, indicating that the inner diameter of the metal cover plate will be equal to the outside diameter of the base support plate. The snap features will be placed equidistant along the circumference of the base support plate.

2. Redesigning the bosses on the base support plate:- The thickness of the bosses should be 40 to 60% of the thickness value of the wall to which they are attached to. In the figure shown (fig.1)

below, all the bosses violate this design guideline and hence either we should increase the wall thickness or reduce the thickness of the bosses.

71



Fig.1 While redesigning the thickness of the bosses it should be taken into consideration that the height of the bosses should not be greater than

2.5 to 3 times the boss thickness. An appropriate draft needs to be given to each boss (fig. 2) and a radius at the base of the bosses, to ease the manufacturing of the mold

and reduce sharp corners on the mold.

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Fig.2

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3. Redesign of the base joint:- 1. Holes for rod:-

Fig.1The holes to be manufactured to pass the rod through them, which would then be used to locate springs, can be manufactured in a different way. Instead of drilling holes in the sheet metal and then welding a rod, passed through these holes, we can increase the thickness of the sheet metal by a small value, and then extrude some material from the surface to substitute as hooks for aligning the three springs. This can be done by extruding material sideways from the side walls and upwards from the bottom surface of the joint.

2. Height of the U-channel:- For a U-channel, the length of base should be less than or equal to the side length. In case of our part, the length of both the sides is greater than 38mm (length of the base, as shown in fig.1). However, the height of our base joint is a lot more than required, which increases material consumption, as well as demands a need for a greater bend arc radius. This problem can be eliminated by reducing the height of the side walls of the base joint and keeping it at an appropriate value, less than 121mm but greater than 38mm.

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Fig.1

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4. Redesigning linkages:-

Fig.1 Fig.2

The linkages shown in fig.2 are too complicated, and will take a longer time to be machined and manufactured. Also, the two movable joints shown shaded in red, only provide rotation about one axis, as shown in the fig.2 by dark arrows, thus limiting the movement of the lamp neck and hence the bulb attached to it. The linkage between the base support and the cone cover at the top, needs to be flexible to give a rotation of 360 degrees (ideally). The design shown in fig.1 replaces the conventional linkage design, and gives it more flexibility, more degrees of freedom and hence close to ideal degrees of rotation, thus increasing the utilization of the lamp as per user requirements.

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Part C:- DFM Concurrent costing analysis:-Elbow joint female:-

Fig.1 Fig.2The female joint shown above will require a complicated mold design considering the geometry of the part, and the parting line of the mold, which also accommodates the side action for the slot (shown in green color in section view of fig.2). This part can be redesigned such that it resembles the male joint shown in Fig.5 below. Two such joints can be attached together using a pin with sufficient tensile strength. Hence, to give an estimate of cost analysis (the reduction in manufacturing cost) both the parts have been analyzed in the Concurrent costing software, and their reports are shown in fig.3 and fig.4.

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Fig.3

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Fig.4

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Fig.5

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Fig.6

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Fig.7

The regions encircled in fig. 6 and 7 show the categories which have been assumed. The number of cavities was found by trial and error method. The optimum number of cavities which does not increase the cost per part by a huge margin and provides the least (or comparatively less and affordable) tooling investment was chosen.

Fig.6 shows the analysis of the actual female joint, while fig.7 shows the analysis of its substitute.

Base joint:-

Fig.1

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Fig.2

The region encircled in dark red in fig 2 shows the features that will be added to the profile cut part. There will be two holes and one bend. The region encircled in red show the details of the further operations to be performed on the part after its profile cutting.

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Fig.3The design analysis of this part shows that we would prefer to reduce the complexity of the linkages between the top cover and base of the lamp, by replacing all the linkages in between by a flexible neck linkage, thus giving the users liberty of moving the lamp light where ever they want to.

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Base Support:-

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Fig.1The number of cavities was found by trial and error method. The optimum number of cavities which does not increase the cost per part by a huge margin and provides the least (or comparatively less and affordable) tooling investment was chosen.

Fig.2

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Fig.3

The only redesign change that the base support requires is decrease of thickness of the bosses. The only contribution it will provide is reduction of total material used. Along with that we need to eliminate the holes on the part which do not serve any purpose, since the part is joined to the base metal cover using a snap fit.

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Design for Assembly

Assembly plan with sequence:

The above figure shows the sequence of assembly. There are 5 sub-assemblies and the numbers are in order of how these are put together in sequence. The same thing in detail has been done in SolidWorks showing each sub assembly separately with sequence of pats coming together. Note: For detail of sequence in SolidWorks please check the group file Drawings_Final Project_LAMP_DFM.SLDDRW.

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1. Base Part:

Fig1: Base Part

a> This part can get nested thus increasing or decreasing the radius or adding rib or flame can help avoiding the problem.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

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2. Base Joint:

Figure2: Base Joint

a> This part can’t get nested or tangled thus follow DFA guidelines.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

3. Base Support:

Figure3: Base support

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4. Elbow Joint Female:

Figure4: Elbow Joint femalea> This part can’t get nested or tangled thus follow DFA guidelines.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> The part can be assembled by pyramid assembly.f> The past has sharp edges on the right end and thus giving little chamfer will help easy insertion.

5. Elbow Joint Male:

Figure5: Elbow joint Male93



a> This part can’t get nested or tangled thus follow DFA guidelines.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> The part can be assembled by pyramid assembly.f> The past has sharp edges on the right end and thus giving little chamfer will help easy insertion.

6. Head Shade:

Figure6: Head Shadea> This part can get nested thus increasing or decreasing the radius or adding rib or flame can help avoiding the problem.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

7. Joint:

Figure7: Joint

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8. Joint1:

Figure8: Joint1


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9. Joint2:

Figure9: Joint2


10. Joint3:

Figure10: Joint3a> This part can’t get nested or tangled thus follow DFA guidelines.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.

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d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

11. Light bulb:

Figure11: Light bulba> This part can’t get nested or tangled thus follow DFA guidelines.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

12. Pivots:

Figure12: Pivots

a> This part can’t get nested or tangled thus follow DFA guidelines.

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b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

13. Springs:

Figure13: Short and long spring

a> This part can get tangled as it has open ends and thus I can lead to more time in assembly as to take them out of the box will need operator to untangle them and then use.

b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

14. Struts:

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Figure14: Struts


15. Socket:

Figure15: Socket

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16. Wheel:

Figure16: Wheela> This part can’t get nested or tangled thus follow DFA guidelines.b> The part is not extremely small, sharp or flexible thus will not slow down assembly time.c> Part is symmetric so orientation is easy.d> Part can be handled with left or right hand with ease and will not require aid of other hand for it.e> This part will have no problem in insertion.f> The part can be assembled by pyramid assembly.

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DFA costing and time:

Executive Summary DFA:

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Assembly time analysis:

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Cost Analysis of assembly:

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Redesign:

The lamp has too many linkages and adding them to the main base takes lot of time as they need to be fixed with the help of springs and each spring takes 8.60 sec in the assembly and thus three springs take 25.80 seconds of the total assembly time of 134.77 seconds. Adding to it is the time of the sub assembly 2 which consists of all the linkages and joints. This assembly is too time consuming as parts need to be aligned properly and then with the help of joints pivoted together and all this process of sub assembly 2 takes 61.66 seconds.

Thus we can redesign the whole subassembly 2 and replace with just a single flexible metal rod and thus eliminating the need of all the linkages of assembly 2 and also the springs and wheels to attach subassembly 2 to the base. This way we can reduce the existing assembly to a very simple assembly of link with very few parts.

Executive summary:

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Redesign assembly time and cost:

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Thus it can be seen that vast difference is obtained in the assembly time by replacing the subassembly 2 with a flexible metal rod and base.

Time (s) Cost ($)

Assembly 134.77 116.94

Re-design 48.73 26.86

The above table summarizes the redesign process and it can be seen that assembly time and cost had reduced a lot after the redesign.

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Appendix

Team Member Contributions

Report N1: Karina Vasquez:

- Project proposals. - 3D model selection. - Report N1- Parts and Subassemblies section. - Report N1- Solidworks disassembly. - Project plan proposals. - Report N1 - Review of each section and corrections.

Abhimanyu Joshi: - Project proposals. - Report N1- Introduction.- Report N1- Project Description

Hrishikesh Khamkar: - Project plan proposals. - Report N1- Project Plan - Report N1- Manufacturing processes and materials assignment.

Report N2: Karina Vasquez:

- 3D model verification. - Import of parts to solidworks. - Sketches definition. - Improvement of the solidworks parts selected. - Solidworks Animation. - Solidworks drawings and BOM. - Report 2.

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Abhimanyu Joshi: - Review.

Hrishikesh Khamkar: - Project Gantt Chart. - Support.

Report N3:Karina Vasquez:

- Review of part analysis and constructive feedback about redesign ideas.- Dimensional drawings with manufacturing tolerances and represented redesign ideas in dimensional drawings.

Abhimanyu Joshi:- Assisted in part analysis, majorly for the base support.- Provided constructive feedback about redesign ideas.

Hrishikesh Khamkar:- Detailed design analysis of the selected parts along with solid work models.- Analysis and Redesign of all the selected parts.- DFM costing analysis of each part and comparison of cost improvements for redesigned features.

Report N4:Karina Vasquez:

- Decided assembly sequence and drawing of sequence and sub assemblies.- Review of DFA analysis.

Abhimanyu Joshi:- Analyzed all parts for compliance with DFA guidelines.- DFM analysis in DFM concurrent software of all parts for DFA analysis. - Costing and time analysis with DFA software.- Redesign of the lamp and costing and time analysis of the new design with DFA software.- Comparison of cost and time of original design with redesign.

Hrishikesh Khamkar:- Provided the redesign idea for DFA.- Review of DFA analysis and consructive feedback in deciding the assembly sequence.

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Design for manufacturing & assembly report (table lamp)

Technology

Transcript of Design for manufacturing & assembly report (table lamp)