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Machine ToolOctober 2009

Did You Know...

Contents...

U nderstanding challenges to accuracy and being able to judge m easurem ent concepts

help in gaining an insight into m easuring technology and m achine tools. That can be

im portant, for exam ple, w hen selecting a suitable m achine tool for your ow n applications,

especially if production quality has a high priority. In this article, w e are placing em phasis

on the accuracy of rotary axes.

In contrast to conventional 3-axis

m achines, 5-axis m achining has

com pletely new dem ands in term s ofaxis accuracy. It is not only a question

of the precision of individual axes here,

but of their accuracy in the w orking

space. A s a result, how ever, the

num ber of error sources is significantly

increased by the higher num ber of

m echanical com ponents in the m achine

design. D epending on the specific

m achine design, angle m easurem ent

is of particular im portance here.

What sources of error exist?

The m any m echanical com ponents of a m achine are all possible sources of errors.These are all stressed by the enorm ous dynam ics of the w orking processes.

5-Axis M achining: Gett ing a Gripon the Accuracy of Rotary Axes

continued on next page

P a g e

2

P a g e

3 Distributor Profile:Automation & Metrology, Inc.

P a g e

4 Chris Weber on LongLength Scales

P a g e

P a g e

P a g e

6

8

7

Leine & Linde 800 SeriesRotary Encoders

Dear Abbe:What is a PWM 9?

1Dplus Encoder

Cover story continued

ND200 Digital Readout

Technical TidbitTorque in Servo Motors

P a g e

5 Increase CNC Accuracywith KinematicsOpt

Stone Contour System s’ Contourjet 510

w ith H EID EN H AIN ’s iTN C 530 control and

scales, and ETEL’s linear m otor.

Typical causes for inaccuracies are:

•W ear caused by high m echanical loads, for

exam ple, or collisions during m achining

•Elasticities in transfer elem ents, e.g., the

w orm shaft, or instabilities of the bearings

•G eom etric errors e.g. radial eccentricity of

m echanical transfer elem ents or incorrectly

installed com ponents

How can sources of error be avoided

or reduced?D uring the design of a m achine, sources of

error in connection w ith the rotary axes should

be ruled out as far as possible. A s a part of the

kinem atic influences, different m echanical and

control-oriented designs of rotary axes should

be com pared.

R otary axes feature com plex m echanics w ith

various com ponents subjected to possible

sources of error. O ptim al com pensation w ould

have as a prerequisite the recognition of all

…that m ultiple H EID EN H A IN com ponents

and system s, including H EID EN H A IN’s

iTN C 530 contouring control, are critical

com ponents of innovative ultra-precise

w aterjet cutting m achines? Because an

ultra high-pressure w aterjet m achine’s

ability to erode and cut through stone or

m etal is highly dependent on a sm ooth,

consistent velocity, its m easurem ent and

feedback com ponents m ust be reliable

and in sync. This is w hy S tone C ontour

System s in C olorado uses HEID EN H A IN

com ponents for their custom er solutions

serving the tile and stone industry.

B esides using the H EID EN H AIN

control, these Stone C ontour m achines

also include the LID A 487 exposed

linear scales that provide the precision

positional feedback to the iTN C 530.

The 20 m icron signal period of the

1vpp signal enables som e very precise

tuning and the resultant tight control

loop is applied to linear m otors from

ETEL a H EID EN H A IN sister com pany

providing direct drive linear m otors that

are inherently contam inant tolerant).

This system translates to super sm ooth

velocity pro les w ith dram atically higher

feedrates and better nishes being easily

attainable w hen the w aterjet’s m otion can

be controlled w ith such precision.

Stone C ontour w aterjet cutting m achines

are highly regarded and also unique in

the level of positional accuracy applied to

w hat is com m only regarded as a crude

process. Part accuracies of +/-.0005”

are readily attainable w ith no sacri ce in

cutting speeds.

Frequently m ulti-axis saw s are com bined

w ith w aterjets to allow alm ost lim itless

shapecutting w ith high throughput.

continued on next page

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possible error sources for every

situation. A nd exactly that is not

possible.

A possibility for getting a grip

on position deviations of rotary

axes is the use of a suitable

H EID EN H A IN angle encoder. For

better understanding of the effect,

here are tw o basic strategies for

the design of rotary axes in control

loops:

–“Sem i-C losed Loop”

If the position of the rotary axis is

m easured solely via the rotary encoder on the m otor, then w e

refer to a “sem i-closed loop”. N ot only is the lack of accuracy ofthe m otor encoder significant w ith this arrangem ent, but m any

other errors also play a part such as w ear, elasticity deviations

and geom etric errors of the m echanical transfer elem ents.

–“Closed Loop”

If an angle encoder m ounted directly on the rotary axis is used

for position m easurem ent, m ost sources of error can be avoided.

This m ethod is know n as the “closed loop”m ethod. U se of

an angle encoder w ith integral bearing is recom m ended in this

respect so that the previously described elasticity deviations

do not lead to additional angle deviation. W hen using an angle

encoder w ith integral bearing, it is presum ed that the m inim al

angle error of an axis lies w ithin the system accuracy of the angle

encoder (the accuracy of an angle encoder of ± 2’’corresponds

to a deviation of ± 5 µm for a table diam eter of 1 m ).

O f course spatial deviations also accum ulate due to elasticity

of the axes. A ngle encoders w ith integral bearing and a hollow

shaft have an additional advantage: an integrated coupling that

com pensates for shifts of the axis m idpoints w ithout additional

angle errors. O n the other hand, angle encoders w ithout integral

bearing w ould lead to eccentric deviations and w ould therefore

provoke additional angle errors.

Are direct drives a

positive trend?

W ith respect to accuracy, direct

drives have several advantagesand hardly any disadvantages.

In the m id-term , an extensive

transition from m echanical

transfer elem ents w ith servo

m otors to direct drives (torque

m otors) can be expected. The

decisive advantage is the very

stiff coupling of the drive to

the feed com ponent w ithout

any other m echanical transfer

elem ents. This is of true

significance for a high level of contour constancy and optim al

surface quality.

W ith the use of direct drives, an additional rotary encoder

for speed definition is required. Position and shaft speed are

defined by the angle encoder m ounted directly to the rotary

axis: a “closed loop”. Since there is no m echanical transm ission

betw een the speed encoder and the feed unit, the angle encoder

m ust have a correspondingly high resolution and signal quality in

order to allow exact speed control, particularly at slow speeds.

Conclusion

System errors can be avoided w ith the selection of suitable

m easuring technology. That applies in particular to rotary axes.

B ecause of their com plexity, accuracy is a m ajor challenge.

Especially w ith interpolated 5-axis m achining and direct drive

technology, encoders that do not convert unavoidable spatial

deviations into large-scale angle errors are recom m ended.

This challenge can be m astered w ith angle encoders (w ith

integral bearing, integrated coupling and absolute position

m easurem ent) directly m ounted on the rotary axis (such as

the RC N m odel).

continued on page 3

Did you know continued from Page 1

2

Because of this, the iTN C 530 w as a natural

control choice for these m ultiprocess system s.

“The iTN C 530 adapts easily to com plicated

pallet and toolchanging system s allow ing

m any processes to be com bined in a singlecoordinate system ,”said C raig Lally, President

of Stone C ontour System s. “This includes W et

Routers utilizing diam ond tooling, as polishing

tooling w ears quickly and often necessitates

very dynam ic tool m anagem ent.”

The organized and ef cient interface of the

iTN C 530 control allow s m ultiprocess

system s to be operated m ore gracefully than

PC controls that are m ore com m on in the

industry. The exibility of program m ing inH EID EN H A IN conversational (.h) or ISO G code

(.i) accom m odates any operational situation.

Shops new to C N C can easily program in this

m ethod w ith FK (free contouring) function

being especially useful in countertop design.

Those w ith existing C A D /CA M can quickly

be adapted to the iTN C 530 w ith de nable

M codes and cycles to m atch their other

equipm ent. The N C interface is clean enough to

be foisted upon even the m ost novice operator.O EM de nable soft keys can com m and any

system process or cycle allow ing com plicated

operations to be reduced to a single, graphical

soft key.

5-axis machining continued from Page 1

HEIDENHAINangle encoder

Rotary axis

Rotary tableof the toolmachine

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continued on page 43

The best solution is angle encoders w ith integral bearing,

integrated coupling and absolute position m easurem ent,

directly m ounted to the rotary axis.

Angle encoders

The term angle encoder is typically used to describe

encoders that have an accuracy better than ± 5”.

In contrast, rotary encoders are encoders that typically

have an accuracy w orse than ± 12”. A ngle encoders

are found in applications requiring precision angular

m easurem ent to accuracy w ithin several arc seconds.

These include rotary tables and sw ivel heads on m achine tools,

C axes of lathes, m easuring m achines for gears, printing units

of printing m achines, spectrom eters, telescopes, etc.

The follow ing m echanical design principles can be defined:

•Angle encoders w ith integral bearing, hollow shaft

and integrated stator coupling

•Angle encoders w ith integral bearing for separate

shaft coupling

•Angle encoders w ithout integral bearing

5-axis machining continued from Page 2

Focusing on high technology

in both product offering

and m arketing has givenH EID EN H AIN distributor

Autom ation & M etrology Inc.

(AM I), headquartered in the

Cleveland, O hio area, a leg up

in the industry. O riginating in

1987 by a form er H EID EN H A IN

em ployee, AM I has grow n to

becom e a key distributor for

H EID EN H AIN in a relatively

short period of tim e, w ith

tw o current O hio locations,

Cleveland and Cincinnati.

“W e pride ourselves on

providing high quality

H EID EN H AIN product,

installation and service for all types of m achines in not only the

M idw est or tri-state area, but also outside of our im m ediate

geographic,”said A M I partner, M ark C ontorno, w ho purchased

the business in 2003 w ith D ave D enm an. “O ur business has

grow n ve-fold since joining the rm a decade ago. D ave and I

have strong strategies in place and have operated consistently

w ith double-digit grow th.”AM I’s custom er base –w hile in

m achine tool, aerospace, bearing

m anufacturing and m edical

equipm ent –varies in theirrequirem ents, they have all com e t

expect the com m itm ent to integrit

and service exhibited by A M I.

B oth currently in their 30s,

M ark and D ave em brace new

technologies and are alw ays

nding w ays in w hich to w ork w ith

them . “Besides the regular use

of online m arketing opportunities

using the H EID EN H AIN nam e to

reach prospects, w e also are rm

believers in regular com m unication

to our existing custom ers,”said

M ark, “O ur custom ers are alw ays

being updated on the latest

H EID EN H AIN technology being offered. W e invest in regular visits

to our custom ers w hich keeps our nam e fresh in their m inds w he

a new application com es up.”

Although A M I approaches the m arket w ith young eyes, they are

w ell rooted in w ays of the past. “Richard W alsh, the previous

Distributor Profi le: AM I Finds Ways to GrowCleveland, OH

For comparison: Accuracy of linear axes

A s w ith angle encoders, linear encoders can also significantly

increase the accuracy of feed axes. A nd here as w ell –as

is often the case w ith H EID EN H A IN –m any influences arerendered unim portant by the design: If a linear encoder is

used for m easurem ent of the slide position, the position

control loop covers the com plete feed com ponent.

Play and inaccuracies in the transfer elem ents of the

m achine have no influence in this case on the accuracy of

the position m easurem ent. M easurem ent accuracy reallyonly depends upon the precision and installation location

of the linear encoder.

AM I partners M ark Contorno and D ave Denm an

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ow ner, helped us understand w hat it takes to run a successfulsm all business,”said M ark. “This is truly paying off during

these dif cult econom ic tim es. And Rick G los (now retired

H EID EN H AIN vice president) w as a great infl uence to m e as I

started out representing H EID EN H AIN .”

W hat m akes A utom ation and M etrology successful? “W e believe

that our ‘claim to fam e’is our know ledge and ability to handle

repairs w ithin 24 hours,”said M ark. “For exam ple, because

of our full stock and in-house equipm ent in our Cleveland and

Cincinnati of ces, a custom er can com e in w ith an encoder issue

and w e can rebuild it w hile he w aits. For jobs further aw ay, w e

pride ourselves on the ability to be on site on any national job

w ithin 24 hours, and x the problem quickly.”

N ot going unnoticed, AM I has received m ultiple aw ards from

H EID EN H AIN , including tw o H EID EN H AIN D istributor of Year

President aw ards (2007 and 2003), as w ell as ten H EID EN H AIN

D istributor of the M onth aw ards over the years. “W e are thrilledto w ork w ith H EID EN H A IN and it is our rst choice w hen w e

retro t any m achine. A M I has offered other brands in the past

but over the past num ber of years, w e have m igrated to the

H EID EN H AIN brand exclusively”said M ark. “The product is

alw ays being developed and this has given us a com petitive edge

in our m arket.”

N ot only does A M I have great con dence in the product, they

also believe in the m anagem ent. “The m anagem ent and the

support are outstanding. O ur com pany know s w e can pick up

the phone and get our problem s solved, w hether it is a technical,

delivery or support issue. Just for these reasons alone, it has

m ade it easy for us not to offer any alternative to H EID EN H AIN .”

Because of AM I’s dedicated focus on m otion control technology,

they cite strong know ledge of the H EID EN H AIN product line,

w hich often saves their custom ers m oney. “W ithout this

know ledge, you are just a quoting m achine,”said M ark. “W e

specify the right com ponents for the job and get the installation

or repairs right the rst tim e. W e are strong believers in

exam ining old technology and enhancing it w ith new and all that

that has to offer.”

For more information about AMI, visit www.auto-met.com

Distributor Profile continued from Page 3

W hen it com es to big

m achines, and I m ean really

big m achines, feedback

requirem ents can be

challenging. Traditional

feedback m ethods includedsystem s such as “rack

& pinion”, low accuracy

m agnetic tapes, draw

w ire encoders, and glass

butted to glass, but all of

those system s involved

com prom ises, typically w ith regards to accuracy and long

term stability. For over 20 years, H EID EN H A IN has been

m aking sealed linear encoders for lengths of up to 100 ft

and beyond, and doing so w ithout com prom ise.

H EID EN H A IN’s longest scale system s are the LB s w hich

utilize a reflective stainless steel tape w ith a gold graduation

(currently 40 µm ) as the m easuring standard providing a

one-piece m easuring system w ith 5 µm /m eter accuracy.

A series of alum inum extrusions are used to house this

tape providing protection from contam ination and anaccurate m ounting surface. Tw o end caps secure the tape

and provide a pre-determ ined tension factor. The beauty of

stainless steel is that it has a sim ilar coefficient of expansion

as the m achine itself and in m any cases the w orkpiece thus

m itigating therm ally induced errors.

The LB system is available in standard version and m irror

im age version (for gantry applications), and w ith its distance-

coded reference m arks, a very short traverse w ill re-establish

By Chris W eber, Product M anager, M achine Tool

Going to Great Lengths with HEIDENHAIN Scales

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5

reference position. G one are the days of m oving long axes to

one end of the m achine to reestablish hom e position.

The aircraft industry has been the chief recipient of the

benefits of this system in recent years in applications from

w ing spar m anufacturing,

to drilling/riveting, carbon

fiber placem ent and

w aterjet cutting. W ith

aircraft getting larger

(A 340 and 787), the LB

382 scales system has gained in popularity and m arket share.

H EID EN H A IN C orporation recently sold and installed tw o of

these LB system s in M ichigan, each w ith a travel of over 240’

(look for a feature article on this application in a future issue of

H eidenhaIN FO ).

In fact, in the last 20 years, H EID EN H A IN has sold over 130

m iles of LB scale system s around the w orld, w hich is roughly

equivalent to driving from Los A ngeles to San D iego or

W ashington D C to P hiladelphia.

So w hat does the

future hold? C urrently

under developm ent is

the absolute version

of this scale w hich w ill

feature the purely serial

EnD at 2.2 interface providing not only long m easuring ranges

but also no requirem ent to reference, as w ell as the ability to

transm it not only position but also additional data betw een the

m easuring and control system s. Stay tuned.

Great Lengths continued from Page 4

H EID EN H AIN LB scale

C om m itted to providing continuous advancem ents in the area

of user-friendly CN C s, H EID EN H A IN C orporation now offers

a new option to its already versatile iTN C 530 contouring

control, m aking possible the autom atic

m easurem ent and com pensation

of m achine angular axes. C alled

Kinem aticsO pt, this new softw are option,

coupled w ith a m ounted H EID EN H A IN

touch probe into the C N C m achine

spindle, increases the accuracy of this

already high functioning control. The

iTN C 530 can control up to 13 axes

and a spindle.

The introduction of Kinem aticsO pt

is the answ er to C N C accuracy

requirem ents becom ing increasingly

stringent, particularly in the area of 5-axis

m achining. W ith Kinem aticsO pt, it does

not m atter w hether the individual axis

being m easured is a rotary table, tilting

table or sw ivel head. The m easurem ent

process is the sam e.

The procedure begins after having defined the m easurem ent

resolution and the area of each rotary axis that is to be

m easured. The operator then initiates probing of a calibration

ball fixed at any position on the m achine table.

From the m easured values, the iTN C 530

calculates the statistical tilting accuracy, w ith the

Kinem aticsO pt softw are m inim izing the spatial

error arising from the tilting m ovem ents.

A t the end of the m easurem ent cycle, the m achine

geom etry is saved in the respective m achine

constants of the kinem atic table. A com prehensive

log file is also saved, recording the actual

m easured cycles and the optim ized dispersion

(m easure of the statistical tilting accuracy) as

w ell as actual com pensation values.

This softw are developm ent follow s other

H EID EN H A IN productivity-enhancing control

additions such as the follow ing:

•Adaptive Feedrate C ontrol (A FC )

•D ynam ic C ollision M onitoring (D C M )

•D XF C onverter

HEIDENHAIN Increases CNC Accuracy w ithNew KinematicsOpt

Kinem aticsO pt-TS740

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6

W ith the introduction of the Leine &

Linde 800 Series rotary encoders, parent

com pany H EID EN H A IN C orporation now

offers a line of encoders that are regarded

am ong the m ost robust, m aintenance-free

and cost effective encoder solutions on

the m arket today. In addition, this series

can optionally be offered w ith A D STM

(A dvanced D iagnostics S ystem ), a built-

in system used for condition-based or

preventative m aintenance, guaranteeing

the reliability of the intended application.

The Leine & Linde 800 Series encodersare w idely used for m otor feedback in the

paper & pulp, steel and m ining industries

w orldw ide. They have also becom e the

m arket’s leading choice for generator feedback in

w ind turbines.

The 800 Series com es in shafted and hollow -

shafted versions, w ith the ceram ic bearing

option m axim izing encoder lifetim e. The series

is characterized by a dynam ic and flexible range

of pulse rates and electrical output com binations

including a dual encoder solution. For hazardous

applications, explosion-proof ATEX-certified

encoder options are offered.

The 800 Series is one of the cornerstones in

the Leine & Linde product portfolio w here highquality flexible encoder solutions that m ake use

of state-of-the-art technology are the essence of

the business.

A nsw ering the dem and for a single-axis position display that

could be m ore fully integrated into a m achine data transfer

netw ork, H EID EN H A IN introduces the N D 200 S eries D igital

R eadouts (D R O s). This display series hosts m ultiple inputs, is

flexible in its configuration, is suitable

for future absolute length gauges and

features com prehensive functions.

These new est single-axis N D 200 D R O s

com e in tw o variants: the N D 280

featuring standard functions (w ith

m onochrom e flat screen) to fulfill

m any m easuring tasks and the N D 287

(w ith color flat screen) w hich is m odularin design and allow s up to four inputs.

This feature allow s toggling betw een m ultiple gauges,

sensors and encoders to be done easily.

W ithin the H EID EN H A IN N D 287, three additional axis

m odules are incorporated. Tw o of them are analog, w hich

perm it the connection of analog sensors (such as tem perature

and pressure) and purely serial EnD at 2.2 units, w hich allow s

for the connection and full use of absolute encoders. A lso,

this D R O can be integrated into the Ethernet facilitating

rem ote m onitoring.

SPC (Statistical Process C ontrol) is now also available on

the H EID EN H A IN N D 287, allow ing the ability to w rite up to

10,000 m easured values to an internal m em ory and evaluate

them statistically.

B oth the N D 200s com e equipped w ith

a card for gauge hookup (com m on use)

and are an im provem ent over past

H EID EN H A IN single-axis D R O s as they

sport new features. A m ong these are

the ability to design functional equations

to m anage interconnected operations of

m ultiple axes and soft keys, w hich provide

m any benefits w ith regard to operationand param eter setting. These units can

display both linear and angle/rotary encoders, as w ell reading

distance-coded reference m arks. Encoders w ith E nD at 2.2 can

be connected to both.

The height and w idth of the both units result from the

requirem ent that they be suitable for installation in a 19-inch

rack. This m akes it possible to m ount tw o position displays

side by side in an electrical cabinet of this standard.

Heavy Duty 800 Series Encoders fromL& L Hold Tough in Rough Environments

Leine & Linde m odel 862, a robust

increm ental encoder solution and a

top choice for harsh environm ents

New HEIDENHAIN DRO Systems for GaugingGive More Opt ions to Netw ork

Single-Axis N D 200 D RO s

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HEIDENHAIN’s Revolutionary2-Dimensional Encoder

Introducing an exciting new

dim ension to m easurem ent,H EID EN H A IN C orporation presents

the 1D plus encoder. A fter m uch

R & D , this uniquely innovative tw o-

dim ensional encoder w as designed

in order to allow m easurem ent

of linear guiding and therm al

drift errors during m ovem ents

of a stage or m achine, allow ing

the processing and im m ediate

com pensation of these errors. This

results in a system w ith very high

accuracies w ith jobs done right the

first tim e.

The m ost likely current applications for the 1D plus include use

in stacked stages, precise gantries, w afer processing, and in

large flat panel display production and tests, though any m otion

stage user w ho w ants to increase perform ance w ould benefit.

These truly revolutionary 1D plus encoders are frictionless

and have gratings in tw o dim ensions, w ith m odels featuring

tw o or three scanning units for sim ultaneous m easurem ent

of both the X and Y directions. Three scanning units allow

the calculation of the angle

of rotation of the bracket thathouses the scanning units.

These orthogonal encoder

graduations provide an exciting

new dim ension in precision as

the encoder system m easures

left and right (X axis), the up-

and-dow n (Y axis) m otion is

m easured (and com pensated for

by the control) as w ell.

H EID EN H A IN ’s early and current

1D plus encoders are in use as

the H EID EN H A IN interferential-

type linear encoder, the LIF 400 w ith 1D plus (see im age).

The m easuring standard is D IA D U R w ith a therm al expansion

coefficient of 0 ppm /K. C urrent m easuring length is 300 x 2

m m , w ith plans to increase that dram atically. The 1D plus scale

itself is 20 x 4.9 m m .

The X-axis m easurem ent of the1D plus has a current accuracy

grade of ± 1 µm and includes a reference m ark. The grating

period of the encoder is 8 µm ; the signal period is 4 µm .

Technical Tidbit:

Torque in Servo Motors

W hen specifying servo m otors for a new m achine or C N C

retrofit, there are m any specifications regarding servo

m otor perform ance. O ne of the m ost confusing is the

differing torque specifications of the m otor. Torque can be

specified in N ew ton m eters (N m ) or m ore com m only foot

pounds (lb-ft) or inch pounds (lbf-in).

1N m = 0.74 lbf-ft = 8.85 lbf-in

Torque (also called m om ent of force) can be defined as:

The m echanical w ork generated by the turning effect

produced w hen force is applied to a rotational axis. O r the

m easure of how m uch a force acting on an object causes

that object to rotate.

R ated Torque (M N ) - The m axim um continuous torque

available at the rated speed that allow s the m otor to do

the w ork w ithout overheating (typically specified at a

tem perature). This is the w orking range of the m otor.

Stall Torque (M O ) - The torque, w hich is produced by

a device w hen the output rotational speed is zero or

the torque load that causes the output rotational speed

of a device to becom e zero –i.e. to cause stalling.

M ax. Torque (M m ax) - A lso know n as peak torque, the

greatest am ount of torque the m otor can generate for

a very short tim e period (typically specified in m s).

W hen specifying servo m otors for a m achine tool

application, the com m only accepted specification is

the R ated Torque.

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8

Answer: The P W M 9 is a com plete universal m easuring unit

for inspecting and adjusting H EID EN H A IN increm ental linear

and angle encoders. Instead of offering just a series of LE D s

on the encoder for installation w hich

can lead to a green light that could

just be m arginally green and cause

issues after the m achine has shipped

to the custom er, H EID EN H A IN offers

tw o devices that provide detailed

inform ation on the encoder signals

and allow s the user to install correctly,thereby increasing the safety m argin

and quality of the m achine overall.

First, the sm all low cost handheld

device that displays am plitude

inform ation to a resolution of 0.1V and

the quality of the hom e pulse is called

the P W T. There are various PW Ts for

the various electrical interfaces and

are dedicated to that interface, such

as 1Vpp or TTL. The other device, a

PW M 9, how ever has this PW T m ode

as w ell as m uch m ore detail about

the encoder signals, such as phase

angle of sine and cos w aves, encoder current consum ption

and encoder voltage and offsets. The PW M 9 has a slot w here

various electrical interface cards can be inserted, such as Endat

(increm ental analog signals only), TTL, and 1V pp. PW M 9 is

G erm an for Phasen W inkel M essung w hich translates to P hase

A ngle M easurem ent, and it is the 9th iteration of this device.

The PW M 9 is also valuable for safe

inline usage so that a user can look at

the detailed encoder signal param eters

w hile the m achine axis is put to m otion

This helps the users to determ ine if

the encoder is installed correctly and

w ith enough safety m argin throughthe w hole range of m otion of that

particular axis. Encoders w ith LED s

cannot com pare as one does not know

if certain areas of the m otion axis are

m arginally “green”or not. Encoders

using just a U SB interface for setup also

cannot be run inline w ith the m achine

axis in m otion.

The PW M 9 has a m onochrom e backlit

LC D screen that is easy to read from

any angle. It also contains 3 B N C

sockets for testing encoder outputs

on an oscilloscope, w hich is probably

the best w ay to install encoders as the lisajous pattern is very

visible and easy to interpret w ith the proper training.

Dear Abbé...

PW M 9 show n in PW T m ode.

Providing answers to questions of accuracy

Question: What is a PWM 9?

HEIDENHAIN CORPORATION333 E. State P arkw ay, Schaum burg, IL 60173

1-800-233-0388 •info@ heidenhain.com

w w w .heidenhain.com

CONTACT INFORMATIONFor m ore inform ation about H EID EN H AIN and

any of the products or services m entioned here,please feel free to contact us.

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