DRAGON INNOVATION, INC. !

DESIGN  FOR  MANUFACTURING  !

COURSE 3: SELECTION OF MATERIALS AND PROCESS !!!!!!!

SCOTT N. MILLER | CEO | @DRAGONINNOVATE | WWW.DRAGONINNOVATION.COM

Start by Minimizing Part Count !

(Why?)

Calculate Theoretical Minimum Number of Parts

1. Relative Motion?

2. Different Material?

3. Required Separate for Assembly?

Questions to Ask for Each Part

Calculate The Assembly Index

• I_DFA = 100 * N_m * T_m / T_a

• Calculate minimum number of parts required (N_m)

• Assume ideal assembly time of 3 sec / step (T_m)

• Itemize each step and estimate actual assembly time (T_a)

• Calc ratio of theoretical time / actual time.

• Low volume electromechanical: 25% is a good target.

PROCESS AND MATERIAL SELECTION

Process & Materials Selection

• Selection of P&M early in the design is critical.

• Consider all options, while keeping in mind CM’s capabilities and applying common sense.

• Part, assembly and materials are closely linked to process.

• Reduce number of secondary ops (i.e. cost).

• Design Decisions will cast a long shadow - it is expensive in time and money to switch later.

• There are techniques to hedge your bets.

Late Stage Changes Are Expensive

Great Reference

M&P Considerations

• Production Volume

• Tooling Budget

• Schedule

• Experience and Design Tools

• Part Geometry

• Service & Environmental Req’s

• Aesthetics

• Accuracy

Example

Shape Attributes • (D1) Depressions: Yes • (UW) Uniform Wall: Yes • (US) Uniform X-Sect: Yes • (AR) Axis of Rotation: No • (RX) Regular X-Sect: No • (CC) Captured Cavity: No • (E) Enclosed Cavity: No • (ND) No Draft: Yes !

Material Req • Max Temp 500C • Corrosion Resistance to Weak

Acids and Bases

Source: Product Design For Manufacture And Assembly, Boothroyd Dewhurst

Process Comparison

Source: Product Design For Manufacture And Assembly, Boothroyd Dewhurst

Process Comparison

Source: Product Design For Manufacture And Assembly, Boothroyd Dewhurst

Process Comparison

Source: Product Design For Manufacture And Assembly, Boothroyd Dewhurst

Options

• Impact Extrusion

• Cold Heading

• Powder Metal Parts

• Hot Extrusion

• Machining from Stock

• Wire EDM

Process Comparison

Source: Product Design For Manufacture And Assembly, Boothroyd Dewhurst

Rank Processes

Source: Product Design For Manufacture And Assembly, Boothroyd Dewhurst

• Throughput & Batch Size

• Schedule

• Production Rate

• Bottlenecks

• Material Handling

• Cycle Time

• Economics

Process Comparison

Source: Product Design For Manufacture And Assembly, Boothroyd Dewhurst

dragon@dragoninnovation.com