Claremont Polymer Shapes - Plastic and metal parts manufacturer, Ontario, Canada.Claremont Polymer Shapes - Plastic and metal parts manufacturer, Ontario, Canada.
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ACETAL (HOMOPOLYMER/COPOLYMER)
DELRINR   ULTRAFORMR   CELCONR   FULTON-404R

SPECIFICATIONS:

U.S. FEDERAL L-P-392A TYPE I CL I, TYPE I CL II and TYPE II CL I
U.S. MILITARY MIL-P-46137A(MR) TYPE 1 CLASS 20 and TYPE II GRADE A CLASS 25
U.S. ORDNANCE OS-12703
FDA TITLE 21 CFR 177.2480 and TITLE 21 CFR 177.2470
ASTM D4181 GROUP 1 CLASS 1 GRADE 1 and GROUP 2 CLASS 1 GRADE 1

NATURAL COLOUR: WHITE (A/F Blends are MAROON)

A crystalline engineering thermoplastic, ACETAL is produced in HomopolymerDELRINR or CopolymerCELCONR, ULTRAFORMR, etc. type. The Homopolymer is harder, tougher and mechanically stronger. Whereas the Copolymer was more resistance to higher temperatures, hot water and a broader range of pH. The recent development by E.I. Dupont of Type E Homopolymer grade has improved its resistance to hot water and alkali environments. With this advent, there is little difference in chemical resistance between Homopolymer and Copolymer. Due to lower resin cost and ease of processing; Copolymer rods, sheets, strips, tubes, etc. are less expensive. In general, ACETALS possess very good mechanical strength, dimensional stability, creep resistance, fatigue resistance and chemical resistance. One of the easiest of polymers to machine, ACETALS exhibit low moisture absorption, natural lubricity, good wear resistance (but poor grit abrasion resistance) and good electrical insulation properties. ACETALS are unusual among thermoplastics in organic solvent resistance. There are no common solvents at room temperature. Strong acids and oxidizing agents adversely affect the mechanical properties and appearance of both polymers. As with most polymers, ACETALS are degraded by exposure to UV radiation or sunlight. Pigmenting with black almost completely eliminates this problem.

With such a quality material, there are a wide variety of grades available. In addition to the standard uncompounded, un-pigmented grade there are numerous internally lubricated grades, glass filled grades and coloured materials.

ACETALS machine very well indeed, with cuttings breaking cleanly away from the tooling keeping the work piece and cutter free of turnings. Very sharp tools used at high surface speeds and slow feeds produce the best finishes and highest tolerance parts. For this reason high speed steels are recommended with all but the glass filled grades. High tool wear resulting from glass-filled grades may necessitate using carbide tooling. With their very good solvent resistance and low moisture absorption, ACETALS permit the use of a wide range of cutting fluids. Although, in many instances, a compressed gas jet directed onto the tool will provide good results in maintaining a cool cutting edge.

Centering Bell
Copolymer CENTERING BELL
used in a Soft Drink Filling Machine

With their high solvent resistance, ACETALS cannot be properly joined by cements without suitably roughening the surface. This can be accomplished using one of three methods: by sanding with 280A grit emery cloth, by a chemical etching process called SANITIZING or through a gaseous etching process. The chemical or gaseous etch produce bonds of 50% higher shear strength than the mechanical sanding method. Both contact and polar cements are useable with the polar type producing substantially higher shear strength. ACETALS can be ultrasonically and, with proper technique, hot gas welded.

Unfilled Homopolymer and Copolymer are approved by the FDA for direct food contact, at room temperature. All other grades are not approved.

GENERAL PROPERTIES
  ASTM
test
Homopolymer Copolymer
E
TYPE
A/F
BLEND
500
CL
20%
GLASS
ACETRONR M
TYPE
FULTON
404R
SPECIFIC GRAVITY   D792 1.42 1.50 1.42 1.56 1.44 1.41 1.55
TENSILE STRENGTH psi D638 10000 9100 9700 8500 8000 8800 6500
TENSILE MODULUS 105 psi D638 3.8       3.5 4.1  
ELONGATION % D638 60 45 40 7 20 75 7
FLEXURAL STRENGTH psi D790 14100 13500 14000 15000 7000 13000 10000
FLEXURAL MODULUS 105 psi D790 4.20 3.90 4.10 7.30 3.80 3.75 3.50
COMPRESSIVE STRENGTH 10% psi D695 18000 16200 15500 18000 14000 16000  
COMPRESSIVE MODULUS 105 psi D695 6.7       3.2 4.5  
HARDNESS rockwell M D785 M94 M88 M94 M90 M72 M78 M70
  rockwell R D785 R120 R118 R120 R118 R116 R118 R110
IMPACT STRENGTH
(1/2" x 1/2")
ft-lb/inch of notch D256 1.2 1.4 1.4 0.8   1.0 (1/8") 0.6
THERMAL EXPANSION 10-5/F D696 5.8 6.2 7.8 3.5 4.7 4.7 5.4
HEAT RESISTANCE
(continuous air)
F   200 195 190 195 190 210 210
DEFLECTION TEMPERATURE   D648              
@ 266 psi F   277 242 250 315 270 230 200
@ 66 psi F   338 329 336 345 330 316 305
DIELECTRIC STRENGTH v/mil D149 500 380 400 490 320 480 400
DIELECTRIC CONSTANT   D150 3.7 3.1 3.5 3.9   3.7 3.1
DISSIPATION FACTOR 10-3 D150 4.8 9.0 6.0 4.9   1 to 6  
WATER ABSORPTION 24hrs % D570 0.25 0.20 0.25 0.25 0.20 0.22 0.20
FLAMMABILITY in/min D635 1.1 0.8 1.1 0.8   1.1 0.8
BEARING PROPERTIES
WEAR FACTOR, 'K' 10-10-in3-min
ft-lb-hr
D3702 65 13 22 N/A   45 14
COEFFICIENT of
FRICTION (DRY)
                 
against self - static 40 psi   0.19 0.10 0.20 N/A   0.20 0.09
against self - dynamic 40 psi/50fpm   0.15 0.09 0.16 N/A   0.15 0.08
against steel - static 40 psi   0.14 0.14 0.13 N/A   0.13 0.07
against steel - dynamic 40 psi/50fpm   0.21 0.16 0.21 N/A   0.19 0.15
LIMITING PV lb-ft/in2-min @10fpm 4000 10000 7000 N/A   3800 10000
    @40fpm 3600 10800 10200 N/A   3500 10800
    @100fpm 3500 12500 12000 N/A   3400 12500
    @400fpm 2300 9000 8600 N/A   2000 9600
    @1000fpm N/A 5500 5000 N/A   N/A 5500
PLEASE NOTE:
Values shown in the above table are averages and there will be variances from lot to lot. After selecting a material based upon these values, you must conduct tests specific to your application to be assured the material suits your needs.

BEARINGS

A convenient way of determining the suitability of ACETAL in a given bearing is to calculate the PV of the proposed bearing system. If it is lower than shown on the previous page, then the likelihood of the bearing performing well is quite high. If the PV is higher than the LIMITING PV then either the system must be changed; or materials with a higher LIMITING PV must be considered. LIMITING PV is the product of limiting bearing pressure and surface velocity; or bearing pressure and limiting velocity. The limit describes a critical, easily recognizable change that may manifest itself in one or more of the following forms: melting, cold-flow, variable friction and/or a dramatic increase in wear rate. LIMITING PV is also dependent upon ambient temperature, bearing clearances, mating material, lubrication and design of the housing. Claremont Polymer Shapes has all the necessary graphs, charts and tables available to allow us to make the necessary corrections for these factors. Contact us when you are making such calculations and we can provide the help you will need. LIMITING PV values shown on the previous page are un-lubricated, room temperature, on average hardness, 16-micron finish steel shafting using our recommended tolerances. For ACETALS, the maximum, un-lubricated surface velocity is 400 feet per minute.

ROLLERS

As an engineering material, ACETALS are quite commonly used in items like rollers. To determine the feasibility of using ACETAL, we must calculate the load capacity of the ACETAL roller. If the load capacity is greater than the actual load, then chances of a successful application are excellent. For a roller on a flat surface, the load capacity is the product of the diameter, the working width of the roller and a factor; which corrects for pressure at varying speeds. This calculation may be modified to determine the suitability of ACETAL as a roller on another roll.