10-Plastics  Mouldings-Tolerances

1.GENERAL

Deviations from the nominal dimension can not e avoided in the fabrication of plastics mouldings.

Dimensional deviations occurring in the production process may result from a number of causes:

a.     Dispersion in the results of the processing. This is dependent on:

·         Uniformity of the moulding material;

·         The machine setting;

·         The mould temperature;

·         Deformation of the mould under pressure.

b.    Condition of mould:

·         Manufacturing tolerances for the dimension of the mould

·         Wear on the mould;

·         Variations in the position of movable parts of the mould.

The tolerances in this standard are specified on the basis of the above considerations and a large number of measurements derived from practical applications.

2.   FIELD OF APPLICATION

The tolerances in this standard:

are applicable – to the dimensions of plastics mouldings produced from thermoplastic and thermosetting moulding materials by compression moulding, transfer mould, compression injection moulding or injection mould or injection moulding;

are not applicable – to extrusions, blow-moulded or foamed mouldings, deep drawn parts, sintered parts and parts produces by a chip removal machining process. Table 1 gives the appropriate tolerance groups to be applied to the various moulding materials.

3. CONCEPTS

Moulding shrinkage VS

Moulding shrinkage means the difference between the dimensions of the mould  LW  at (23±2)°C and those of the mouldingLF, the letter having been stored for 16 hours after manufacture in standard atmosphere and then measured immediately after:

Radial moulding shrinkage VSR

The radial moulding shrinkage is the moulding shrinkage in the direction of injection.

Tangential moulding shrinkage VSR

The  tangential moulding shrinkage is the moulding shrinkage perpendicular to the  direction of injection.

Moulding shrinkage DVS

The moulding shrinkage difference is the difference between the radial and tangential moulding shrinkage

4.   Tolerances

The tolerances shall apply to mouldings at the time of acceptance; see clause 5.

Unless otherwise agreed, a reference must be made on the drawing to the acceptance conditions as specified in clause 5.

4.1. General tolerances [1]

The numbers specified in table 1, column 4, refer to the appropriate tolerance group in table 2.

If the deviations are not specified against the number for the dimension in production documents, order documents, ect. a note must be included referring to this standard, by specifying                            ALRI 00-01-750-2002 and the tolerance group given in table 2.

Example for specifying tolerance group 140:

DIMENSIONS WITHOUT TOLERANCE

See Norm

ALRI 00-01-750-2002 (140)

4.2. Deviations specified against dimensions [2]

In table 1, columns 5 and 6, two series are given for specifying tolerances against dimensions. The figures in these refer to the appropriate tolerance group in table 2. Series 1 tolerances can be complied with without special measures in production,

The series 1 and 2 tolerances shall be divided into upper and lower deviations in accordance with technical requirements.

Example showing division of tolerance 0,8 :

+ 0,8 or   0 or ± 0,4 or + 0,6 or + 0,3
    0 – 0,8 –  0,2 –  0,5

Note:          If it is required that the tolerances be maintained in respect of effect acting on the moulding from the environment or caused by the condition of the moulding during the production process [3] , this shall be expressly  agreed between the supplier and the customer and specified in drawings, order documents, ect.

4.3. Dimensions related to the mould (see figure 1)

Dimensions in table 2 related the mould are in each case dimensions in the same part of the mould.

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4.4. Dimensions not related to the mould (see figure 2)

Dimensions in table 2 not related to the mould are dimensions determined by the interaction of movable elements of the  mould, e.g. wall thickness dimensions and bottom by the shims or mould slides.

Note:          the tolerances on these dimensions are greater than those on the mould-related dimensions because the movable parts of the mould do not always reach the same final position when the mould is closed.

When the permissible deviations are entered against the dimension, take care to ensure that dimensions lying in the closing direction of the mould all vary in the same direction, i.e. that the bottom thickness for example increases when the overall height of the moulding increases.

For non-mould-related dimensions in the direction of closing of the mould, the values specified in table 2 can be increased if necessary in the case of compression moulding. In such a case the dimensions shall be marked with these increased tolerances.

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4.5. Reduction of tolerances

For perpendicular dimensions tolerances narrower than those specified in table 2 may be obtainable by special measures.

For precision engineering at the present time the last two line in table 2 apply.

4.6. Drafts

Since all deviations apply to the nominal dimensions entered on the drawing, the drawing must clearly show the point on the draft taper to which the nominal dimension applies.

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The size of the required draft tapers must be specified in the drawing.

4.7. Tolerances of and position

Deviations of form and position occurring alter removal from the mould are dependent on the shaper of the mould among other things.

Angular tolerances, tolerances of form and position shall be specified in accordance with DIN 7184 Part 1 directly against the dimension or (where applicable) as general tolerances in accordance with DIN 7168 Part 1 and Part 2.

Example showing method of specifying general tolerance:

Angular tolerances, tolerances of  form and position

DIN 7168 – mT

 

4.8. Tolerances of parts produced by chip removal marching processes

For parts produced by chip removal machining processes, DIN 7160, DIN 7161 and DIN 7172 Part apply.

4.9. Tolerances for threads

The following shall be used as a guideline: tolerance class “coarse” for metric threads, in accordance with DIN 13 Part 14 and tolerance class “B” for pipe threads in accordance with

DIN ISO 228 Part1.

5.   Acceptance conditions

Acceptance shall not take place earlier than 16 hours after manufacture of plastics moulding or after any required post-moulding treatment.

The atmosphere used for acceptance shall be standard atmosphere DIN 50014-23/50-2. For other temperatures and relative humidity’s the measured values must be corrected by taking into account the appropriate coefficients of linear expansions.

Post-moulding treatments (conditioning or hart treatment) shall be agreed between the supplier and the customer.

For plastic parts made of moulding materials for which the change in dimensions- e.g. through moisture absorption or re-crystallization – has to be taken into account in making the measures for acceptance, the type of between to supplier and the customer. It is advisable also to agree that the specified treatment conditions shall apply also to the measurement.

[1] Formerly designed as: “Dimensions without specified tolerance”

[2] Formerly designed as: “Dimensions with specified tolerance”

[3] These could be for example, temperature, atmospheric humidity, gases and vapours, liquids

[4] In the case of unreinforced, partly crystalline, non-hardening moulding materials (thermoplastics) the next highest tolerance group shall apply for wall thicknesses over 4 mm

[5] See page 8

TABLE 1 – CORRELATION OF TOLERANCE GROUPS WITH MOULDING MATERIALS

1 2 3 4 5 6
Symbol for

basic material

Mouldings made from Moulding materials in accordance with DIN Tolerance  group
For general tolerances For dimensions where the deviations are indicates against the dimensions
Series 1 Series 2
EP Epoxy resin moulding materials 130 120 110
EVA Ethylene vinyle acetate copolymer moulding materials 16778         Part 1 140 130 120
PF Phenolic plastic moulding materials Whit inorganic fillers Type: 11.5-12-13-13.5-13.9-15-16 7708 part 2 130 120 110
Whit organic fillers Type: 30.5-31-31.5-31.9-32-51-51.5-51.9-52-52.9-71-74-75-83-84 140 130 120
UF MF Aminoplastic moulding materials and Aminoplastic / Phenolic plastic moulding materials Whit organic fillers Type: 131-131.5-150-152-152.7-153-154-180-181-181.5 7708 part 3 140 130 120
Whit inorganic fillers Type: 155-156-158 130 120 110
Whit organic and inorganic fillers Type: 157-182-183 140 130 120
UP Polyester resin moulding materials Type: 801-802-803-804 16911 130 120 110
UP Polyester resin mats Type: 830-830.5-831-831.5-832-832.5-833-833.5 16913         Part 3 140 130 120
Compounds for cold moulding Type: 212-214 7708 Part 4 140 130 120
ASA Moulding materials based on acrylonitrile-styrene acrylester copolymers 130 120 110
ABS Moulding materials based on acrylonitrile-styrene acrylester copolymers 16772    Part 1 130 120 110
CA Cellulose acetate moulding materials 7742      Part 1 140 130 120
CAB Cellulose acetate butyrate moulding materials 7742      Part 1 140 130 120
CAP Cellulose acetate propionate moulding materials 140 130 120
CP Cellulose propionate moulding materials 140 130 120
PA Polyamide moulding materials (amorphous, whit or without filler) 130 120 110
PA 6 Polyamide 6 [1] moulding materials (amorphous, whit or without filler) 140 130 120
PA 66 Polyamide 66 4moulding materials (amorphous, whit or without filler) 140 130 120
PA 610 Polyamide 610 4moulding materials (amorphous, whit or without filler) 140 130 120
PA 11 Polyamide 11 4moulding materials (amorphous, whit or without filler) 140 130 120
PA 12 Polyamide 12 4moulding materials (amorphous, whit or without filler) 140 130 120
Glass fibre reinforced polyamide 6 – 66-610-11 and 12 moulding materials 130 120 110
PB Polybutylene moulding materials 160 150 140
PBTP Polybutylene terephthalate moulding materials without filler 140 130 120
with filler 130 120 110
PC Polycarbonate moulding materials (whit filler, without filler) 7744      Part 1 130 120 110
PDAP Polydiallyl phthalate moulding materials (with inorganic filler) 130 120 110
PE Polyethylene moulding [2]  (without filler) 16776    Part 1 150 140 130
PESU Polyether sulphone  moulding materials  (without filler) 130 120 110
PSU Polysulphone moulding materials  (with filler, without filler) 130 120 110
PETP Polybutylene terephthalate moulding materials (amorphous) 130 120 110
Polybutylene terephthalate moulding materials (crystalline) 140 130 120
Polybutylene terephthalate moulding materials (with filler) 130 120 110
PMMA Polymethyl  methacrylate moulding materials 7745      Part 1 130 120 110
POM Polyoxymethylene (polyacetal) moulding materials 5 (with filler), length of moulding < 150 mm 140 130 120
Polyoxymethylene (polyacetal) moulding materials 5(without filler), length of moulding  ≥ 150 mm 150 140 130
Polyoxymethylene (polyacetal) moulding materials 5 (with filler) 130 120 110
PP Polypropylene mould materials 5  (without filler) 16774             Part 1 150 140 130
Polypropylene mould materials 5  (glass fibre reinforced, reinforced with talcum or asbestos fibre) 140 130 120
PP/EPDM Mixture of polypropylene and rubber (without filler) 140 130 120
PPO Polyphenylene  oxide  moulding materials 130 120 110
PPS Polyphenylene  sulphide  moulding materials (with filler) 130 120 110
PS Polystyrene moulding materials 7441             Part 1 130 120 110
PVC-U Unplasticized polyvinyl chloride moulding materials 7448             Part 1 130 120 110
PVC-P Plasticized polyvinyl chloride moulding materials 7449             Part 1 No data available at present
SAN Styrene acrylonitrile moulding materials (with filler, without filler) 16775          Part 1 130 120 110
SB Styrene butadiene  moulding materials 16771         Part 1 130 120 110
Mixture of Polyphenylene oxide and polystyrene (with filler, without filler) 130 120 110
Fluorinated polyethylene-polypropylene moulding materials 150 140 130
Thermoplastic polyurethane Products with

70 to 90 Sh A [1]

150 140 130
Products with

over 50 Sh D 6

140 130 120

[6] For Shore hardness tests A and D see DIN 53505
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TABLE 2 – GENERAL TOLERANCES AND TOLERANCES ON DIMENSIONS WHIT DEVIATIONS ETERED AGAINST THE DIMESION

Tolerance group from

Table 1

Code Letter(1) NOMINAL DIMENSION RANGE (in mm)
over 0 1 3 6 10 15 22 30 40 53 70 90 120 160 200 250 315 400 500 630 800
Up to 1 3 6 10 15 22 30 40 53 80 90 120 160 200 250 315 400 500 630 800 1000
General tolerances
160 A ± 0,28 ± 0,30 ± 0,33 ± 0,37 ± 0,42 ± 0,49 ± 0,57 ± 0,66 ± 0,78 ± 0,94 ± 1,15 ± 1,40 ± 1,80 ± 2,20 ± 2,70 ± 3,30 ± 4,10 ± 5,10 ± 6,30 ± 7,90 ± 10,00
B ± 0,18 ± 0,20 ± 0,23 ± 0,27 ± 0,32 ± 0,39 ± 0,47 ± 0,56 ± 0,68 ± 0,84 ± 1,05 ± 1,30 ± 1,70 ± 2,10 ± 2,60 ± 3,20 ± 4,00 ± 5,00 ± 6,20 ± 7,80 ± 9,90
150 A ± 0,23 ± 0,25 ± 0,27 ± 0,30 ± 0,34 ± 0,38 ± 0,43 ± 0,49 ± 0,57 ± 0,68 ± 0,81 ± 0,97 ± 1,20 ± 1,50 ± 1,80 ± 2,20 ± 2,80 ± 3,40 ± 4,30 ± 5,30 ± 6,60
B ± 0,13 ± 0,15 ± 0,17 ± 0,20 ± 0,24 ± 0,28 ± 0,33 ± 0,39 ± 0,47 ± 0,58 ± 0,71 ± 0,87 ± 1,10 ± 1,40 ± 1,70 ± 2,10 ± 2,70 ± 3,30 ± 4,20 ± 5,20 ± 6,50
140 A ± 0,20 ± 0,21 ± 0,22 ± 0,24 ± 0,27 ± 0,30 ± 0,34 ± 0,38 ± 0,43 ± 0,50 ± 0,60 ± 0,70 ± 0,85 ± 1,05 ± 1,25 ± 1,55 ± 1,90 ± 2,30 ± 2,90 ± 3,60 ± 4,50
B ± 0,10 ± 0,11 ± 0,12 ± 0,14 ± 0,17 ± 0,20 ± 0,24 ± 0,28 ± 0,33 ± 0,40 ± 0,50 ± 0,60 ± 0,75 ± 0,95 ± 1,15 ± 1,45 ± 1,80 ± 2,20 ± 2,80 ± 3,50 ± 4,40
130 A ± 0,18 ± 0,19 ± 0,20 ± 0,21 ± 023 ± 0,25 ± 0,27 ± 0,30 ± 0,34 ± 0,38 ± 0,44 ± 0,51 ± 0,60 ± 0,70 ± 0,90 ± 1,10 ± 1,30 ± 1,60 ± 2,00 ± 2,50 ±  3,00
B ± 0,08 ± 0,09 ± 0,10 ± 0,11 ± 0,13 ± 0,15 ± 0,17 ± 0,20 ± 0,24 ± 0,28 ± 0,34 ± 0,41 ± 0,50 ± 0,60 ± 0,80 ± 1,00 ± 1,20 ± 1,50 ± 1,90 ± 2,40 ±  2,90
Tolerances on dimensions with deviations entered against the dimension
160 A 0,56 0,60 0,66 0,74 0,84 0,98 1,14 1,32 1,56 1,88 2,30 2,80 3,60 4,40 5,40 6,60 8,20 10,20 12,50 15,80 20,00
B 0,36 0,40 0,46 0,54 0,64 0,78 0,94 1,12 1,36 1,68 2,10 2,60 3,40 4,20 5,20 6,40 8,00 10,00 12,30 15,60 19,80
150 A 0,46 0,50 0,54 0,60 0,68 0,76 0,86 0,98 1,14 1,,36 1,62 1,94 2,40 3,00 3,60 4,40 5,60 6,80 8,60 10,60 13,20
B 0,26 0,30 0,34 0,40 0,48 0,56 0,66 0,78 0,94 1,16 1,42 1,74 2,20 2,80 3,40 4,20 5,40 6,60 8,40 10,40 13,00
140 A 0,40 0,42 0,44 0,48 0,54 0,60 0,68 0,76 0,86 1,00 1,20 1,40 1,70 2,10 2,50 3,10 3,80 4,60 5,80 7,20 9,00
B 0,20 0,22 0,24 0,28 0,34 0,40 0,48 0,56 0,66 0,80 1,00 1,20 1,50 1,90 2,30 2,90 3,60 4,40 5,60 7,00 8,80
130 A 0,36 0,38 0,40 0,42 0,46 0,50 0,54 0,60 0,68 0,76 0,88 1,02 1,20 1,50 1,80 2,20 2,60 3,20 3,90 4,90 6,00
B 0,16 0,18 0,20 0,22 0,26 0,30 0,34 0,40 0,48 0,56 0,68 0,82 1,00 1,30 1,60 2,00 2,40 3,00 3,70 4,70 5,80
120 A 0,32 0,34 0,36 0,38 0,40 0,42 0,46 0,50 0,54 0,60 0,68 0,78 0,90 1,06 1,24 1,50 1,80 2,20 2,60 3,20 4,00
B 0,12 0,14 0,16 0,18 0,20 0,22 0,26 0,30 0,34 0,40 0,48 0,58 0,70 0,86 1,04 1,30 1,60 2,00 2,40 3,00 3,80
110 A 0,18 0,20 0,22 0,24 0,26 0,28 0,30 0,32 0,36 0,40 0,44 0,50 0,58 0,68 0,80 0,96 1,16 1,40 1,70 2,10 2,60
B 0,08 0,10 0,12 0,14 0,16 0,18 0,20 0,22 0,26 0,30 0,34 0,40 0,48 0,58 0,70 0,86 1,06 1,30 1,60 2,00 2,50
Precision engineering A 0,10 0,12 0,14 0,16 0,20 0,22 0,24 0,26 0,28 0,31 0,35 0,40 0,50
B 0,05 0,06 0,07 0,08 0,10 0,12 0,14 0,16 0,18 0,21 0,25 0,30 0,40
(1)           A = for non – mould –  related dimensions
B = for mould related dimensions

Está disponível para consulta um artigo de referência com a numeração e designação dos diferentes componentes de moldes para matérias plásticas.