The machinability tolerance of resin
The main processing methods for resin are machining and injection molding. Cutting is a processing method of cutting resin using a cutting tool. Injection molding is a processing method of pouring melted resin into a mold for cooling and solidification. The precision of machining is higher than that of injection molding, so the tolerance indication can be more stringent.
Both methods are the same, but it should be noted that due to thermal expansion, the tolerance is the size at the temperature during measurement. In addition, the machining tolerances may vary slightly depending on the material, equipment, and mold accuracy.
The aperture tolerance of machining
For example, in the case of opening holes on the resin, if the diameter is about 10mm, the tolerance may be 0~+0.03. Due to the fact that the size of the hole depends on the size of the drilling tool, high-precision machining can be carried out.
Tolerance of center distance between machined holes and holes
Materials that can handle high-precision machining can be specified with a tolerance of around ± 0.01. On the other hand, POM (polyoxymethylene), which is well-known as a material that is not easily worn, is difficult to process with such high precision, with a limit of about ± 0.05.
The aperture tolerance of injection molding
When specifying an aperture with a diameter of about 10mm, if the hole depth is about 10mm, an aperture of around 0~+0.05 can be specified. Injection molding molds often have a starting angle, so the deeper the hole, the greater the tolerance.
Tolerance of center distance between holes in injection molding
The machinability tolerance of POM (polyoxymethylene) is approximately ± 0.1. Furthermore, even for materials as easy to achieve accuracy as PPS, ± 0.03 is the limit.
Tolerance of sheet metal processing
The main processing methods for sheet metal are bending and cutting. Bending processing usually uses a bending machine to bend metal plates. Most bends are at right angles, but they can also be bent at other angles. Cutting is done using a laser processing machine. Cutting the shape, drilling round holes, long holes, etc.
Aperture tolerance in sheet metal processing
When cutting through laser processing, the aperture can be specified with a tolerance of 0~+0.05. Used for positioning φ In the case of 10 holes, specify as φ 10+0.05/0.
Tolerance of center distance between holes in sheet metal processing
The center to center distance can be specified as a tolerance of approximately ± 0.05.
Tolerance of bending processing
The dimensional tolerance from the center of the reference hole to the bending base is limited to approximately ± 0.15. At the same time, it is necessary to indicate the tolerance of the bending angle.
For example, bending at 90 ° requires a tolerance of around ± 1.0 °. Because even if the tolerance at the base of the bend is ± 0.15mm, there will be further deviation at the top of the bend.
If you also want to indicate the distance from the center of the reference hole to the top of the bend, you need to consider the angle tolerance so that the tolerance is greater than the root.
The tolerance of bars processed by lathes
Metal bars are processed using a lathe. A lathe is a machining method that uses a cutting tool to cut the surface of a high-speed rotating bar. Mainly indicating diameter and axial dimensions.
Diameter tolerance of SUM materials
SUM material is a free cutting steel commonly used for mass production because it is cheaper than SUS. SUM materials are coated with anti rust oil or coatings to prevent rust. Due to differences in the thickness of the coating, if the coating is included, the tolerance range is limited to around 0.03. Indicating as φ 100/-0.03.
Diameter tolerance of SUS materials
If it is SUS material, electroplating is not required, and slightly stricter tolerances can be specified. Can specify φ Around 100/-0.01, with a tolerance range of around 0.01.
Tolerance in the long side direction
The dimensional tolerance in the long side direction can be specified as around ± 0.03.
