design with delrin.pdf
DESCRIPTION
Plastic EngineeringTRANSCRIPT
Delrin®
Acetal resins
Design with Delrin®
Start
with DuPont
Engineering Polymers
® D
uPon
t’s r
egis
tere
d tr
adem
ark
▲ ▲ ▲
Do You Speak Delrin®?▲▲
Introduction
Outstanding Attributes
List of Grades
Low Wear, Low Friction Series
Key Properties Table
Stiffness & Strength
Creep Resistance
Stress Relaxation
Fatigue Resistance
Impact Resistance
UV Resistance
Temperature
Chemical Resistance
Typical Applications
Radii
Uniform Wall Thickness
Ribs
Bosses
Threads
Snap Fits
Rapid Prototyping
Stockists/Machinists
Colours
Processing
Regrind & Recycling
Laser Marking
Medical Applications
Further Reading
Design Basics
Performance
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‘Design with Delrin®’Data at your fingertips
Delrin®
Acetal resins
Design
with
Delrin®
Start
with DuPont
Engineering Polymers
® D
uPon
t’s r
egis
tere
d tr
adem
ark
▲ ▲ ▲
Do You Speak Delrin®?
▲▲
Introduction
Outstanding Attributes
List of Grades
Low Wear, Low Friction Series
Key Properties TableStiffness & Strength
Creep Resistance
Stress Relaxation
Fatigue Resistance
Impact Resistance
UV Resistance
Temperature
Chemical Resistance
Typical ApplicationsRadii
Uniform Wall Thickness
Ribs
Bosses
Threads
Snap Fits
Rapid Prototyping
Stockists/Machinists
Colours
Processing
Regrind & Recycling
Laser Marking
Medical Applications
Further Reading
Samples
Design Basics
Performance
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& Strength
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This handbook makes basic information easily available todesigners and others and gives a quick reminder of theimpressive range of Delrin®
properties.
It is illustrated with a selectionof photographs showing someof the enormous variety ofapplications for which Delrin®
has already been successfullyused.
Use the colourcoded bars to helpyou ‘flick’ through tothe relevant sectionand data
‘Design with Delrin®’
Back to index
Delrin® versatility: snap fits to ski bindings, clips to conveyors,buckles to bicycle parts
Designers – use simple rules
to get the best from Delrin® in
“Design Basics”
View applications
throughout this binder
. . .Do you speak Delrin®? Are you as fluent as youwould like to be?
. . .Are you up to speed withall the new grades includingLow Wear, Low Friction, UVResistant and the ElevenSeries?
. . .Do you know whereDelrin® is used – and why?Have you heard of Delrin®
but don’t know what it feelslike?
. . .This Delrin® “phrase book”will help you brush up onyour acetal knowledge until itbecomes your first language.
Delrin® has a unique blend of
properties – understand them in
“Performance”
▲▲
Do You Speak Delrin®?▲
This publication is also available at http://www.dupont.com/enggpolymers/europe
4 5
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Delrin® versatility: skate parts, ski bindings, speaker grilles
What is Delrin®?Delrin® is an engineeringthermoplastic with a combination ofphysical properties not availableeither in metals or other plastics.
It has a well balanced profile ofmechanical properties, environmentalresistance and processability atmoderate cost.
Delrin® acetal resins providesubstantial strength, stiffness andcreep resistance.
Delrin® has gained widespreadrecognition for reliability ofperformance in many thousands ofengineering components all overthe world.
Since its commercial introduction byDuPont in 1960 it has been used in
the automotive, appliance,construction, hardware, electronicsand consumer goods industries.
I N T R O D U C T I O N
Delrin® acetal homopolymer was introduced by DuPont in 1960.Copolymer acetal followed somewhat later, around 1962.
Typical examples of Delrin® applications appear throughout this handbook
Trade name: Delrin®
Generic name: acetalSub class: homopolymer
Abbreviation: POM (polyoxymethylene)
Structure: highly crystalline polymerized formaldehyde
6 7
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Delrin® versatility: coloured lighters to carousels, pumps to pegs
O U T S TA N D I N G AT T R I B U T E S
This unique balance of properties makes Delrin® suitable for many metal replacement projects
The outstanding attributes of Delrin® acetal resins include:
Toughness at low temperatures(down to –40°C)
High mechanical strength and rigidity
Fatigue endurance unmatchedby other plastics
High resistance to repeatedimpacts
Excellent resistance tomoisture, petrol, solvents etc.
Excellent dimensional stability
Natural lubricity
Resilience
Good electrical insulatingcharacteristics
Ease of fabrication
Wide useful temperature range(in air –50 to +90°C withintermittent use up to 160°C
8 9
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Delrin®: whether standard or specialised, a grade forevery application
100 High viscosity100P High viscosity, easy processing.111P High viscosity, easy processing,
improved stability
500 Medium viscosity 500P Medium viscosity, easy processing511P Medium viscosity, easy
processing, improved stability
900P Low viscosity, easy processing911P Low viscosity, easy processing,
improved stability
1700P Very low viscosity, easyprocessing, improved stability
DE 9156 1,5% PTFE micropowder120MP 20% PTFE micropowderDE 9152 1,5% PTFE micropowder520MP 20% PTFE micropowder500AF 20% PTFE fibres500CL Chemical Lubricant500AL Advanced Lubricant900SP Special Polymer500SC Silicone Concentrate100KM Kevlar® Modified
LIST OF DELRIN® GRADES
Standard Low Wear/Low Friction
100ST Super tough, high viscosity100T Toughened, high viscosity500T Toughened, medium viscosity
Toughened
510GR 10%GR525GR 25%GR570 20%GF577 20%GF, UV resistant
Glass Reinforced/Filled
127UV High viscosity, best UV527UV Medium viscosity, best UV927UV Low viscosity, best UV1727UV Very low viscosity, best UV107 High viscosity, UV507 Medium viscosity, UV
Delrin® 100=high viscosity 500=medium viscosity 900=low viscosity
UV
1110
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Level 1Tribological system
Level 2 Requirements:
how can I avoid...?
Level 3Solution: appropriate
grade of Delrin®
High wear resistanceagainst aluminium
Delrin® 100KM ($$$)Delrin® 500CL ($$)Delrin® 500AL ($$)
($) . . . . ($$$$) = relative cost
L O W W E A R , L O W F R I C T I O N S E R I E S
The natural lubricity of Delrin® means it may be found unlubricated in many gear and bearing applications
Choosing Delrin® is a good starting point for applications inwhich wear and friction are majorissues. Unmodified Delrin® haslow friction and wear against steelas can be seen from the chartbelow.
THE FACTORS AFFECTINGWEAR AND FRICTION ARE:* Pressure of contact* Relative velocity* Temperature* Geometry of motion* Frequency of motion* Nature and finish of surface
* Lubrication
For metal as acounter surface,
the harder the surface the better the wear and
friction behaviour of the system.
Aim for a hardness of greater than
50 HRc
1000
100
10
1
0.00 0.10 0.20 0.30 0.40
P R O T O T Y P E T E S T I N G I S I M P O R T A N T
Spec
ific
wea
r ra
te(1
0-6 m
m3 /N
m)
Dynamic coefficient of friction, µ
Countersurface= steel PPO▲
ABS ▲
PBT▲ ▲ PA66
POM▲(Delrin®)
▲POM+20%PTFE(Delrin®)
New!
high PV
steel
Delrin®
againstmetal
low PV
Delrin® with low specific wear rate, ·ws
Delrin® 100/500/900 ($)Delrin® DE9156/DE9152 ($$)Delrin® 500CL ($$)Delrin® 500AL ($$)Delrin® 100KM ($$$)Delrin® 520MP ($$$)Delrin® 500AF ($$$$)
Wear
Best
Delrin® with low coefficient of friction, µ
Delrin® 100KM ($$$)Delrin® 100/500/900 ($)Delrin® DE9152/DE9156 ($$)Delrin® 500CL ($$)Delrin® 500MP ($$$)Delrin® 500AL ($$)Delrin® 500AF ($$$$)
Friction
Best
friction
wearaluminium
RESIN SELECTOR – DELRIN® AGAINST METAL
wear
Delrin® with low specific wear rate, ·ws
1312
Delrin® 100/500/900 ($)Delrin® 500CL ($$)Delrin® DE9152/DE9156 ($$)Delrin® 500AL ($$)Delrin® 100KM ($$$)Delrin® 520MP ($$$)Delrin® 500AF ($$$$)
Wear
Best
PV= pressure • velocity
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L O W W E A R , L O W F R I C T I O N S E R I E S
Please refer to the grades list for details of Low Wear, Low Friction Resins
When two parts are in contact in a wearsituation it is normal to choosedissimilar materials (eg Delrin® acetaland Zytel® nylon). Factors such asdimensional stability may make such achoice impossible, in which case thenew Low Wear, Low Friction gradesof Delrin® may be suitable. The tablebelow shows the improvement inwear and friction compared tostandard grades.
0.10 0.20 0.30 0.40
Spec
ific
wea
r ra
te(1
0-6 m
m3 /N
m)
New Grades
●900SP
StandardGrades
100P●
10000
100
1000
10
1
Countersurface
= Delrin®
Quieter too!Certain grades reduce noise(squeak) dramatically comparedwith standard grades
. . . continuedLevel 1Tribological
system
Level 2 How can I
avoid...?
Level 4 Solution: otherthan material
choice
Level 3Solution: appropriate
grade of Delrin®
($) . . . . ($$$$) = relative cost
15
friction
impactnoise orfailure
wear
squeak
Non-squeaking grades of Delrin®
Delrin® toughened grades(external lubrication needed)
Delrin®
againstDelrin®
Delrin® 500SC@10% ($)Delrin® 500AL ($$)Delrin® 900SP ($$)Delrin® 120MP/520MP ($$$)Delrin® 500AF ($$$$)
Delrin® with low specific wear rate, ·ws
Delrin® DE9156/DE9152 ($$)Delrin® 500SC @ 5% ($)Delrin® 500AF ($$$$)Delrin® 500AL ($$)Delrin® 900SP ($$)Delrin® 500SC @ 10% ($)Delrin® 120MP/520MP ($$$)
Delrin® with low coefficient of friction, µ
Delrin® DE9156/DE9152 ($$)Delrin® 500AF ($$$$Delrin® 520MP ($$$)Delrin® 120MP ($$$)Delrin® 500AL ($$)Delrin® 500SC @ 5% ($)Delrin® 900SP ($$)Delrin® 500SC @ 10% ($)
Friction
Best
Delrin® 100T ($)Delrin® 500T ($)Delrin® 100ST ($$)
Wear
Best
external lubrication
other material forcounter surface
external lubrication
external lubrication
optimise design
reduce pressure
14
RESIN SELECTOR – DELRIN® AGAINST DELRIN®
●500AL
DE 9152●
●520MP
Dynamic coefficient of friction, µ
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K E Y P R O P E R T I E S TA B L E
Delrin® 100 is the toughest unmodified acetal available with a unique combination of elongation and stiffness
Based on Delrin® 100 high viscosity acetal
Yield stress
Yield strain
Strain at break
Flexural modulus
Izod notched impactstrength @ 23°C
@–40°C
Temperature of
deflection under load
Melt temperature
Flammability
Shrinkage
Melt Flow Index
Chemical Resistance
Density
71
25
70
2800
128
115
177
HB
1,9 to 2,2
2,2
outstanding
1,42
MPa
%
%
MPa
kJ/m2
°C
°C
%
g/10 min
g/cm3
Property Units Value
For graphssee next section
Campusdiskette
available
Delrin®: stiff, strong, tough, chemically resistant
16 17
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The exceptional elongation coupled with stiffness makes Delrin® suitable for snap fits
To judge the stiffness and springiness of Delrin® ask your nearest DuPont Engineering Polymers office for test bar samples.
The modulus of Delrin® isaffected by changes in thetemperature as shownbelow.
3
2
Temperature (°C)
Youn
g’s
mod
ulus
(G
Pa)
1
0 —20 0 20 40 60 80 100
The mechanical response to short term loads
is shown above
Strain (%)
Str
ess
(MPa
)
20
0 0 2 4 6 8 10
40
60
80
-20°C 23°C
90°C
Material chosen and whyDelrin® 100 was chosen for its unique balance of stiffness and strength
Description/ApplicationSnap fit buckle
18 19
P E R F O R M A N C E
Stiffness and Strength
Young’s modulus of Delrin®
as a function of temperature
Stress v Strain at –20°C,23°C and 90°C
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P E R F O R M A N C E
Upon removal of a 14 MPa deforming stress, Delrin® immediately recovers 40% of the imposed strain
Creep is defined as time dependentstrain, resulting from stress.
Str
ess
(M
Pa)
20
15
10
5
00 0,5 1,0 1,5 2,0 2,5
I s o c h r o n o u s s t r e s s / s t r a i nD e l r i n® 1 0 0 @ 2 3 ° C
1h10
h10
0 h
1000
h50
00 h
1000
0 h
Total strain (%)
Creep
Always try to design partsso that they arenot permanentlyloaded
The factors affecting creep are:*Stress level*Time*Temperature
Material chosen and whyDelrin® 100 was chosen for its good spring characteristics and superior creep
compared with polyamide, polypropylene and acetal copolymer
Description/ApplicationClothes peg
20 21
100
000
h
(proje
cted) Delrin® Acetal Resins
have extremely goodcreep resistance for anunreinforced polymer
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P E R F O R M A N C E
Stress free mouldings may be obtained by annealing Delrin®
at 160°C for 45 mins
Stress relaxation is defined asdecrease of the stress required to
maintain constant strain.
% o
f in
itia
l st
ress
100
80
40
20
10
0,01 0,1 1,0 10 100 1000 10000
Te n s i l e s t r e s s r e l a x a t i o n o fD e l r i n®1 0 0 a n d 5 0 0 @ 2 3 ° C
Hours
Stress relaxation
Strain 0,3%. 17 MPa0,9%. 34 MPa
5%. 66 MPa
12,5%.Yield point strain 69 MPa
Stress relaxation is particularlyimportant whenconsidering press-fit assembly
Material chosen and whyDelrin® 100P was chosen for its good friction properties and a balance of
impact and creep resistance with high dimensional stability
Description/ApplicationCar window guides
22 23
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P E R F O R M A N C E
Delrin® Acetal Resins have extremely high resistance to fatigue failure from –40°C to +80°C
Fatigue
When materials are stressed cyclically at high levels of stress in relation to their tensile strength,they tend to fail at levels of stressbelow their ultimate tensilestrength.
This phenomenon is termed “fatigue failure.”
Str
ess
(M
Pa)
50
40
30
20
10
0103 104 105 106 107
C y c l e s t o f a i l u r e
Fatigue failure stress of Delrin®compared withother plastics106 cycles, 23°CMaterial Stress
(MPa)Polycarbonate 10ABS 11Polypropylene 15Delrin® acetal 32
Material chosen and whyDelrin® 100 was chosen for the best balance of stiffness and strength coupledwith flex fatigue resistance needed for the spring fingers of the tool gripper
Description/ApplicationTool changer carousel
24 25
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P E R F O R M A N C E
Delrin® acetal maintains its high toughness down to very low temperatures
Impact resistance is definedas the ability to withstand asudden blow rather than aslowly applied load.
Impact Resistance
60
Charpy Impact Strength (23°C)
Impa
ct s
tren
gth,
kJ/m
2
500 500T 100 100T 100ST
50
40
30
20
10
0
20
15
10
Temperature, °C
Impa
ct s
tren
gth,
kJ/m
2
5
0
R
-40 -20 0 20 40 60
Izod Impact v Temp Delrin 100
See also Effect of Radii in‘Design Basics’
▲
Description/ApplicationRollerblade brake
Material chosen and whyDelrin® 100ST was chosen for the best combination of stiffness and
impact resistance at low temperature, combined with good mouldability
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P E R F O R M A N C E
The Delrin® UV family of resins are well suited for sporting goods and otheritems which are used outdoors but stored indoors
Acetal resins, like mostpolymers, are affected bylight, particularly sunlightwhich includes ultra-violetradiation of wavelength290-400 nm.
UV Resistance
R
Exposure, kJ/m2
Rel
ativ
eG
loss
0
1,0
0,5
500 1000
x27UV BK
x07 BKx00 BK
Exposure, kJ/m2
Rel
ativ
eTe
nsile
Stre
ngth
0
0,5
500 1000
UV Stabilised
Standard
1,0
Accelarated Interior Weatheringaccording to SAE J-1885
Coloured Delrin® resinsoffer some UVprotection. High levelsof carbon black act asan effective UV screenfor non-critical outdoorapplications
Typical values for Delrin® grade 527UV compared with other grades.
Material chosen and whyDelrin® 127UV was chosen for its excellent balance of mechanical
properties combined with good UV resistance
Description/ApplicationMoped brake lever
29
Colours
▲
28
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P E R F O R M A N C E
The thermal stability ofDelrin® means it finds use in applications from –50°C to +90°C
The highly crystallinenature of Delrin® means it is suitable for short-termexposure to temperaturesclose to the melting pointof 177°C.
Temperature
Specific HeatThermal Conductivity(W/m • K)
Key ThermalCharacteristicsProperty
Melt temperatureVicat Softening10 N50 NRelative ThermalIndex (w/o impact)HDT (1,8 MPa)Ball Pressure Test
°C
177
174160
90115165
1 2 5 10
100
75
50
Exposure time in years for which tensile strength in excess of 55 MPa is retained
Air
Tem
pera
ture
(0 C
)
If you need higher temperature resistance,consider DuPont Zytel® nylons , Crastin® and Rynite®
polyesters or Zenite™ LCPs.
Material chosen and whyDelrin® 100 was chosen for its good thermal stability combinedwith a low coefficient of friction and superior impact resistance
Description/ApplicationBearing roll cages
30 31
After 1 yearat 100°CDelrin® retains80% of itstensile strength
0,35
0,30to0,37
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Delrin® has excellent resistance to moisture, gasoline, lubricants, solvents and many neutral chemicals
Do not use Delrin®
in strong acids or
bases outside the
range of pH 4 to 9
CHEMICAL BEHAVIOUR
Acetic acid (5%) resistantAcetic acid (50%) unsatisfactoryAcetone resistantAir (all pressures) resistantAlcohol (all types) resistantAmmonia (10%) unsatisfactoryAniline limited resistanceBenzene resistantBleaching fluid (10% chlorine) unsatisfactoryBrake fluid resistantButane resistantCalcium chloride (10%) resistantCarbon dioxide resistantCarbon monoxide resistantChloracetic acid (10%) unsatisfactoryChlorine gas unsatisfactoryChlorinated water < 0,5 ppm resistantChloroform limited resistanceChromic acid (10%) unsatisfactoryCitric acid resistantCyclohexane resistantDetergents resistantDiesel fuel resistantEthanol resistantEthyl acetate resistant
P E R F O R M A N C E
Chemical Resistance
The factors affecting
chemical resistance are:
* Concentration
* Time
* Temperature
* Stress Level
14 Alkali
9
7 Neutral
4
0 Acid
Description/ApplicationPool cleaner swivel bearing
Material chosen and whyDelrin® 500P was chosen for its excellent wear properties, chemical
resistance, snap-fit ability and dimensional stability
32 33
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P E R F O R M A N C E
CHEMICAL BEHAVIOUR
Ethyl ether resistant
Ethylene glycol resistant
Formaldehyde (37%) resistant
Formic acid unsatisfactory
Fuel oil resistant
Gasoline resistant
Glucose (sat.sol.) resistant
Heptane resistant
Hexane resistant
Hydrochloric acid (10%) unsatisfactory
Hydrofluoric acid unsatisfactory
Hydrogen peroxide (1%) resistant
Hydrogen peroxide (30%) unsatisfactory
Hydrogen sulphide unsatisfactory
Insecticides resistant
Isoctane resistant
Jet fuel /kerosene resistant
Lubricating oil resistant
Methyl chloride limited resistance
Methylene chloride limited resistance
Methyl ethyl ketone limited resistance
Mineral oil resistant
Motor oil resistant
Nitric acid (10%) unsatisfactory
CHEMICAL BEHAVIOUR
Nitrous acid unsatisfactory
Nitrous oxide (dry) unsatisfactory
Oils (food) resistant
Oils (mineral) resistant
Oleic acid resistant
Palmitic acid resistant
Paraffins resistant
Perchloric acid (10%) unsatisfactory
Phosphoric acid (30%) unsatisfactory
Phthalic acid resistant
Potassium hydroxide (10%) unsatisfactory
Propane (liquified gas) resistant
Sodium chloride (10%) resistant
Sodium hydroxide (10%) unsatisfactory
Sodium hypochlorite (5%) unsatisfactory
Sulfur dioxide unsatisfactory
Sulphuric acid (30%) unsatisfactory
Tetrahydrofuran resistant
Toluene resistant
Trichloroacetic acid unsatisfactory
Trichloroethane (1,1,1) resistant
Turpentine / white spirit resistant
Urea (5%) resistant
Vinegar resistant
Chemical Resistance cont.
Material chosen and whyDelrin® 500P was chosen for its good petrol resistance,
good mechanical properties and ease of moulding
Description/ApplicationFuel level device
34 35
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T Y P I C A L A P P L I C AT I O N S
The exceptional balance of properties has led to a diverse use ofDelrin® around the world
Ski Bindings
Clips Door Handles Fuel Systems
Zips Conveyors
Fasteners Speaker Grilles
Lighters Gears
Toughness @–40°CUV performance
Strength,stiffness, lowwear, low friction
Low friction, brightcolours
Elongation, fatiguestrength
Stiffness, low friction,UV performance
Chemical resistance
Economical, toughness Easy flow, impact performance
Low wear, quietoperation
Chemical resistancePressure vessel
Do it in Delrin®. . .
. . . nothing does it better
36 37
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D E S I G N B A S I C S
Delrin® like many plastics, is notch-sensitive but unlike other resinsit has high impact strength at low temperatures
Str
ess
Fac
tor
R/T
Radii use of radii has three main functions* Reduces notch effect * Helps material flow* Eases ejection frommould
see also
ImpactPerformace
▲
Always use radii
at rib junctions
and stressed areas
but also consider
thread terminations,
knurled inserts and
surface textures
Material chosen/Design commentDelrin® 111P was chosen for this application. Radii lowers stress
concentration when parts are put under load
Description/ApplicationSpring clips
38 39
0 0,2 0,4 0,6 0,8 1,0 1,2 1,41,0
1,5
2,0
2,0
Usual
P = Applied LoadR = Fillet RadiusT = Thickness
P
T
R3,0
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Even wall section will greatly benefit highly crystallinepolymers such as Delrin®
Even wall thickness
gives:
* Even shrinkage
– less distortion
* Even set-up
– quickest moulding
cycle
* Less material
– low cost
Choosing the correct wallthickness for a moulded partis a function of end useconstraints (what does thepart have to do?), moulding factors, (what is the thinnestsection that can be moulded?)and overall cost.
The exact thickness may beestimated by the use of FiniteElement Analysis (FEA) usedin both part design and flowanalysis, but where possibleshould be relatively constant throughout.
D E S I G N B A S I C S
Uniform Wall Thicknesses
Description/ApplicationRatchet mechanism
Material chosen/Design commentDelrin® 500P. Low distortion and cost efective part ensured
by use of even wall thickness
40 41
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If ribbing is unacceptable, Delrin® 510GR and 525GRoffer significant increase in stiffness
Ribs are an effective way
to improve the rigidity of
moulded parts.
For Delrin®, ribs should be
1/2 to 2 /3 the general wall
thickness, with 1/4° to
1/2°draft angle per side.
Sink marks caused byribs may be hidden
by use of textured surface orsuitable interruption in thearea of the sink.
D E S I G N B A S I C S
Ribs
Proper use of ribs will:
* Save material and weight
* Shorten moulding cycle
* Eliminate voids in thicksections
Description/ApplicationCross beam
Material chosen/Design commentDelrin® 100P enables increased stiffness to be achieved by
use of ribs without compromising surface finish
42 43
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Weld lines should be avoided in bosses. Delrin® being generallyunreinforced, has excellent weld line strength
D E S I G N B A S I C S
Bosses are used for
mounting purposes or for
reinforcement around holes.
As a rule the outside
diameter of a boss should be
2 to 3 times the hole
diameter.
Heavy sections may be
avoided by stepping the boss
off the adjoining wall.
Use radii at all junctions.
Always use screws designed forplastics when consideringassembly. These may be singleor twin-start threaded ortrilobular screws. Repeatedassembly and disassembly ispossible with Delrin®.
Bosses
Boss Design
***
Hole dia = 0,75 x nominaldia of screw
Boss dia : 2 to 3 times hole dia
Hole depth 2 x nominalscrew dia minimum
Description/ApplicationFuel flange
Material chosen/Design commentDelrin® 511P. Boss and linking rib design
provides accurate hole centres
4544
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D E S I G N B A S I C S
When required, threads maybe automatically mouldedinto the part, eliminating theneed for mechanical thread-forming operations.For external threads, it maybe possible to locate theparting line on the centre ofthe thread.For internal threads, anautomatic unscrewing deviceis used in the tool.
To avoid ‘squeak’ on heavilyloaded threads, consider theLow Wear, Low Friction gradesof Delrin®
Use of a buttress
type thread will
avoid unnecessary
radial forces on
the mating part
Correct termination of threads
▲
The dimensional stability ofDelrin® makes it very suitable for the moulding of accurate thread forms
Threads
Description/ApplicationIndustrial valve
Material chosen/Design commentDelrin® 500P. Moulded thread form avoids machining
4746
1mm
Round threads
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The combination of stiffness and elongation makesDelrin® very suitable for snap fits
L
R
D E S I G N B A S I C S
Snap Fits are a cost effectiveway of assembling partstogether without the use ofspecial tools.
Usually the parts are at restbefore and after assemblyand pass through a stressedcondition as the snap fit ismade to work.
With Delrin®, a single use snapfit may be stressed up to 8%strain (Delrin® 100). For afrequently used one refer tothe fatigue stress graph
Snap Fits
Delrin® is also excellent forcircular and spherical snapfit designs
Cantilever Snap Fits
***
Make ‘L’ as long
as possible
Taper snap fit lug
Use radii at root
▲
Description/ApplicationCable guide
Material chosen/Design commentSnap fit in Delrin® 500 gives strong, rattle-free connection
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Prototyping tipsKeep heat generatedduring machining to aminimum
Support thin wallsand long partsBe aware of the notcheffect of machiningparts
R A P I D P R O T O T Y P I N G
Delrin® has excellent machining characteristics using conventional tools
In order to test parts in the actualmaterial it is normally necessaryto mould them. Due to the easeof machining of Delrin®, it maybe possible to prototype partsby NC machining, utilising theCAD data which describesthe part geometry.
ModifyGeometry
Mould Parts
7
5a
*
*
*
Delrin®
stockists/machinists
▲Shoehorn prototype
CNC machining of simple shapes possible in Delrin®
50 51
CAD Data
1
Test Parts
5
NC MachineMould Tool
6
Hand Finish
4
Create Tool
Paths
Machine Stock Shapes(Block, Rod)
32
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S T O C K I S T S / M A C H I N I S T S
Details of companies experienced in machining Delrin® acetal resinsare also available from your DuPont representative
Contact your DuPont representative for detailedinformation on your local Delrin® stockist
Rod stock, slab
Always ask for Delrin® by name
52 53
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C O L O U R S
No heavy metals are used in Delrin® Colours
Typical referencecodes for
Delrin® colours
I d e a l l y a n y m a s t e r b a t c h s h o u l d b e a c e t a l b a s e d
NC = Natural
BK = Black
WT = White
GY = Grey
GN = Green
BL = Blue
YL = Yellow
RD = Red
Pigmentsmay affectshrinkage –test first!
Custom colours areavailable as fully
compounded productfrom DuPont or bymasterbatch from pigment suppliers
S h r i n k a g e v. C o l o u r
NC
WT
YL
BK
BL
GY
RD
GNCOLOUR
SHR
INK
AG
E(%
)
2,1
2,0
1,9
1,8
Delrin® The heart of a good product
54 55
1,7
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For specific processing information ask for the free booklet‘Delrin® Moulding Manual’
The most important variablesin producing good parts by
injection moulding are:
Above all, a good qualityhomogeneous melt is required.
* Melt temperature
* Injection speed
* Hold pressure
* Screw forward time
* Mould temperature
Always dry toughened gradesfor 4 hours at 80°C
P R O C E S S I N G
Melt Temp(°C)
215 90 100 8 30 1,9 - 2,2
MouldTemp(°C)
HoldPressure
(MPa)Hold PressureTime (s/mm)
Max Hold Up Time
(min)Shrinkage
(%)
Typical set-up conditions forDelrin® 100 are shown below.
Material chosen and whyDelrin® 927UV was chosen for its excellent mouldability and impact resistance.
Its resistance to UV and easy colourability are additional assets
Description/ApplicationVenting system grille
5756
Grades based on the ‘P’ stabilisation system are suitablefor hot runner tools,these include
100P, 500P, 900P,1700P127UV, 527UV, 927UV,1727UV,111P, 511P, 911P.
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R E G R I N D & R E C Y C L I N G
It is important to use analytical techniques in part design to reduce the impact of recyclate on the environment
RECYCLING
The combination of
stiffness and elongation
that makes Delrin® so
effective in snap fits also
means that parts may be
disassembled prior
to recycling.
The long term stability
of Delrin® means that
parts may be reground
and remoulded with
little effect on
properties.
Incineration is an energy
efficient alternative
>POM<
Description/ApplicationGolf tee
Material chosen and whyDelrin®100 regrind was chosen for the shank. Capable ofwithstanding high impact, it provides the correct rigidity
5958
REGRIND
Up to 25% of properlyground sprues and runners may be mixedwith virgin resin with little or no effect onmechanical properties.Toughened grades willneed to be dried priorto moulding.For glass reinforcedgrades, use a slow speedon the grinder rotor.
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L A S E R M A R K I N G
See also Delrin® colours
Laser marking is particularly suitable when
the batch sizes are small and marking variability is required
(e.g. serial numbers or different languages).
. . .BK-L01 Black
. . .BL-L01 Blue
. . .BN-L01 Brown
. . .GN-L01 Green
. . .GY-L01 Grey
. . .RD-L01 Red
. . .WT-L01 White
Advantages* High rate contactlessprocess
* Flexibility, easy changeof layout and charactertype
* No surface pre-treatment,no solvent, no ink* High durability of themarking
A range of colours specially optimised for laser marking is available in Delrin®.Tested with severalNd:YAG lasersystems, thesecolours provide highcontrast markingswith almost noengraving
LASER = Light Amplification by
Stimulated Emission of Radiation
Colours for laser marking 500LM ...
▲Material chosen and whyDelrin® 500LM BK-L01 was chosen for its clarity of laser marking
plus its mechanical properties
Description/ApplicationSki adjuster
6160
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M E D I C A L A P P L I C AT I O N S
Delrin® acetal resin is notcertified for implants
Do not use DuPont materials in medicalapplications involving
permanent implantation in thehuman body or permanentcontact with internal body
fluids or tissue.
Do not use DuPont materials in medical
applications involving brief ortemporary implantation in thehuman body or contact withbody fluids or tissues unless
the material has been provideddirectly from DuPont under a
contract which expresslyacknowledges the
contemplated uses.
For food contact or pharmaceutical
applications, regulatorycompliance statements are
available, please contact your local DuPont
representative fordetails.
DuPont makes norepresentation, promise,express warranty or impliedwarranty concerning thesuitability of these materialsfor implantation in the humanbody or in contact withinternal body fluids or tissues.
✠CAUTION
✚
Description/ApplicationMedical tube clip
Material chosen and whyDelrin® 500P was chosen for its chemical resistance and springiness
6362
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F U R T H E R R E A D I N G
The general brochure covering all DuPont engineering polymersis called ‘From concept to commercialisation’
To access furtherinformation concerningany topic covered in this
binder, please contactyour local DuPont office
Access information onDelrin® at our internet
address:http://www.dupont.com/
enggpolymers/europe
Delrin® Product guide and properties
DesignInformation
MouldingManual
Main Literature for Delrin®
▲▲
▲
▲
DuPont has a wide
selection of literature
covering specific
application areas
such as Appliances,
Automotive, Electrical,
Furniture etc.,
together with a
General Design Principles
handbook which covers all
DuPont engineering resins
Technical Information
A wealth of experience available in various formats64 65
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Delrin®. Chosen for reliability of performance in many thousands of engineering components all over the world
Delrin® Makes the Difference
66
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