Some standard content:
China State Shipbuilding Corporation Department Standard
CB867-83
General Technical Conditions for Plastic Parts
Published on February 13, 1984
Implemented on October 1, 1984
China State Shipbuilding Corporation Department Standard
General Technical Conditions for Plastic Parts
CB 867-83
Group: 82
Replaces CB867-76
This technical condition applies to thermosetting plastic parts and thermoplastic plastic parts (hereinafter referred to as parts) molded by compression molding and injection molding for torpedoes.
1 Technical Requirements
1.1 The performance indicators and storage conditions of plastic materials shall meet the requirements of the corresponding technical conditions. 1.2 The surface of the parts shall be flat and glossy, and no bubbles, pores, cracks, looseness or external impurities are allowed. Its finish is guaranteed by the mold (the finish of the mold surface should generally not be less than √9). 1.3 The color of the natural color of thermoplastic plastic parts should be basically consistent with the color of the raw materials. The color difference of the colored parts should not be significantly different from the first sample of the same batch.
1.4 Thermoplastic fiber reinforced plastic parts are allowed to have a small amount of fiber bundles (limited to not affecting the strength), but the surface must not be exposed.
The general surface of the parts is allowed to have the following phenomena without affecting the use: local loss of gloss and dullness.
Minor scratches caused by demolding.
The text, pattern, and symbol on the parts have slight scratches, but they cannot affect their clarity. The confluence marks formed by the flow of plastic. Due to the shape and structure of the parts, some gases and low-molecular volatiles are not easy to be eliminated during the molding process or the mold is eroded, resulting in pitting and different gloss patterns in some parts, and a small amount of bubbles, depressions, and ripples. f.
For light-colored thermoplastic parts (such as light blue, light green, milky white, etc.), small black spots and needle-like color spots are allowed. Burrs that are difficult to remove due to structural limitations are allowed. The recess of the ejector mark shall not exceed 0.5mm.
The uneven surface of the part caused by the mold insert should be within the dimensional tolerance range. For thermosetting fiber reinforced plastic parts, there shall be no delamination. A small amount of resin concentration is allowed, and its depth should not exceed 1/3 of the thickness of the part.
The collapse of the head and tail of the plastic thread shall not exceed 1/4 of the thread. 1.6Www.bzxZ.net
Under the condition that it does not affect the use, the following phenomena are allowed for parts with metal inserts: a.
When it does not affect the electrical performance, a small amount of metal particles are left on the surface of the part. The recess or protrusion of the insert on the surface of the part shall not exceed 0.3mm. Due to the different shrinkage of the insert and the plastic, the surface of the part is raised. 1.7
Requirements for additional processing of parts
The burrs and gates of the parts should be completely removed and trimmed, but the body should not be damaged. The sharp corners of the parts are allowed to be chamfered by 0.1~0.3×45°, or rounded by R0.3. When the sharp corners or gates collapse, the chamfer is allowed to be 1.7.2
0.3×45° or rounded by R0.5~～1.
After additional processing, the parts are allowed to have the following phenomena without affecting the use: a.
Machining marks and minor scratches near the processing, minor scratches on metal inserts. A protective layer can be applied to the damaged coating as needed. For threaded inserts, when burrs need to be removed with a tap, the coating is slightly scratched. China State Shipbuilding Corporation issued on February 13, 1984 and implemented on October 1, 1984
CB867-83
The surface of thermosetting plastic parts after additional processing can be coated with corresponding resin paint as needed. 2 Dimensional tolerance
The dimensional tolerance of plastic parts shall be in accordance with Table 1: the selection of accuracy grade shall be in accordance with Table 2.
Basic size
>10~14
>14~18
>18~24
>24~30
>30 ~40
>40~50
>50~ 65
>65~80
>80~100
>100~120
>120~140
>140~160|| tt||>160~180
>180~200
>200~225
>225~250
>250~280||t t||>280~315
>315~355
>355~400
Basic size
>400~450
>450~500.
CB867-88
Continued Table 1
Note: ① Table 1 only specifies tolerances, while the upper and lower deviations of basic dimensions can be allocated as needed, ±1/2 of the difference.
Generally, the hole is positive (+), the axis is negative (-), and the length is the tolerance of the mold. ②The dimensional tolerance affected by the active part of the mold is shown in Figure 1, which is the sum of the tolerance value and the additional value in Table 1. The additional value of level 2 accuracy is 0.05mm, the additional value of level 3~5
accuracy is 0.1mm; the additional value of level 6~8 accuracy is 0.2mm. 6
Note: a-
Movement direction of the movable part of the mold
Dimensions not affected by mold movement;
Dimensions affected by mold movement.
(Example)
Polystyrene
Acrylonitrile-butadiene-styrene copolymer (ABS) Polymethyl methacrylate
Polycarbonate
Polyphenylene ether
Phenolic plastic powder
Amino plastic powder
30% Glass fiber reinforced plastic
Polyamide (Nylon) 6, 66, 610, 9, 1010 Chlorinated polyether, polyvinyl chloride (hard)
High precision
Recommended accuracy level
General accuracy
Low accuracy
(Example)
Polyoxymethylene, polypropylene, polyethylene (high density) Polyvinyl chloride (soft), polyethylene (low density) CB86788
Continued Table 2
Note: ①Other materials can be processed according to dimensional stability; refer to the above table to select the accuracy level. ②1, 2 level precision is precision level, only used under special conditions. High precision
③When the dimensions at both ends along the demoulding direction are required, the influence of demoulding slope on precision should be considered. 2.2
The tolerance of the dimension without tolerance shall be in accordance with the 8th level specified in Table 1. 2.3
The deformation of plastic parts should be within the tolerance range. Recommended precision level
General precision
Low precision
The thread precision shall be in accordance with the internal thread 7H and external thread 8n specified in GB197-81 "Ordinary thread tolerance and fit (diameter 1~355mm)". For non-interchangeable parts installed once, the thread precision is allowed to exceed the tolerance, but it must meet the use requirements according to the test. 2.5
There should be a blank on the threaded parts (see Figure 2), and its size shall be in accordance with Table 3. Figure 2
1.25~1.75
The thread start and end dimensions L are shown in Figure 3. The external thread should remove 1/4 of the circumference, and the internal thread should retain 3/4 of the circumference. Q
CB86783
2.7 The length, chamfer, transition radius, taper and angle tolerances of the parts shall comply with CB829-82 "Regulations on Products Without Tolerances".
2.8 The demoulding slope of the parts shall be within the tolerance range. 2.9 The dimensions of the complete set of parts can be coordinated during production without affecting assembly. 3 Inspection of parts
The surface quality of the parts should be inspected in full. 3.1
3.2 Dimension inspection: When the parts are tested, all dimensions must be inspected (the parts should be parked at room temperature for 24 hours, and the parts that need heat treatment should be parked at room temperature for 24 hours after treatment). During the production process, only the main dimensions are sampled, with no less than 3 pieces per batch. 3.3 Samples may be selected for comparison when necessary.
3.4 When conducting internal stress test on thermoplastic plastic parts, no less than 3 pieces shall be tested for each batch (the tested parts cannot be used again). If the parts fail to meet the requirements, the test shall be repeated. If the parts fail to meet the requirements again, the batch shall be scrapped. Test method: Solvent immersion method is adopted, that is, the parts are immersed in a specific solvent. If no cracks appear within 2 minutes, the parts are qualified. The solvents used for immersion of some thermoplastic plastic parts are shown in Table 4. Table 4
Plastic name
Polystyrene and its copolymers
Polyamides
Polycarbonate, polysulfone, polyphenylene ether, etc.
Polymethyl methyl acrylate and its modified products
Packaging, storage and transportation
Parts shall be packaged and marked according to different requirements (the date must be indicated). 4.1
Solvents used
N-heptane
Carbon tetrachloride
Boiled water
4.2For thermoplastic products, the packaging materials are not allowed to contain substances that corrode the corresponding plastic materials. Products should be stored in an environment with a temperature below 35°C, a relative humidity of less than 80%, no acid, alkali and other chemically corrosive gases in the surrounding air, and no direct sunlight.
Products should be protected from collision, severe vibration and rain during transportation. 4.4
Additional instructions:
This standard is under the jurisdiction of 725.
This standard was drafted by 872.
The main drafter of this standard is Wang Zhongyang.
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