In cutting, the cost of machining varies depending on the dimensional tolerances of machining accuracy, difficult shapes, and the ease of machining of the material.
Since the points for cost reduction vary greatly depending on the application, we would like to explain them here by dividing them into machining method, machining shape, machining material, and dimensional tolerance.
Plastic processing methods include cutting, molding, and 3D printing, and there are a variety of processing methods from prototyping to mass production.
As explained in the material selection section, plastic materials are used in a variety of ways depending on their physical properties, and there are situations where plastic materials are selected based on limited usage conditions (heat resistance, abrasion, sliding properties, etc.) or where the material is changed from metal to plastic to reduce weight.
By listening to the customer’s intended use, we hope to propose processing that not only reduces costs, but also provides cost performance that will benefit both the ordering and receiving sides.
We can consider various processing methods, such as cutting or 3D printing for prototypes and small lots, cutting for medium lots, and molding for mass production.
When dimensional accuracy and surface roughness of the cutting surface are not necessary, there is also a finish called saw-cut, which is just sawing.
Although O.M. specializes in plastic processing, we have built a network of partner companies in various fields, and we are ready to answer any questions you may have, even in different fields.
The more complex the machined shape, the higher the machining cost, and the tighter the dimensional accuracy of the part, the higher the machining cost again. There are several points that can be taken into consideration to prevent cost increases.
1. hole machining, especially long hole machining and dimensional accuracy in the 1/100 mm range. Long hole processing requires the use of a special cutter, which may cause vibration of the cutter and melt the plastic processing if the hole is too deep.
2. If a corner part must be R or C-chamfered instead of thread chamfered (C0.5 or less), the machining cost will increase due to the additional process.
3. Curve machining using a ball end can be performed with CAD/CAM, but the machining time is longer, resulting in higher machining costs.
The materials to be processed vary in cost depending on the weight and size of the material. As for board materials, for acrylics, 1100mm x 1300mm of fixed length, 910mm x 1820mm of subrock board, and 1000mm x 2000mm of meter board are commonly used at O-M, but there are also 1200mm x 1800mm of shiroku board, 1200mm x 2400mm of shihachi board, and so on.
We also have engineering plastics and super engineering plastics 500mm x 1000mm, 1000mm x 1000mm, etc. Expensive materials can be cut into appropriate sizes, called “free cutting. Bars are usually available in 1000L (1m) and 2000L (2m), but more expensive materials such as super engineering plastics are also available in 300L and 500L. Bars can also be free-cut.
Processing fees also vary greatly depending on the ease of processing the material.
Among the types of plastics, material and plastic processing costs may vary depending on the type of material, with some materials being inexpensive and others being expensive.
General-purpose plastics < engineering plastics < thermosetting resins < super engineering plastics
Processing cost
General-purpose plastics < engineering plastics < thermosetting resins = < super engineering plastics
This is a rough estimate, but we hope you can use it as a reference.
We have all types of plastics in stock, including general-purpose, engineering plastic, super engineering plastic, and thermosetting plastic.
As is often the case with dimensional tolerances, the dimensional tolerances of plastic processing are different from those of metal.
Tolerances on plastic are harder to achieve than on metal.
The primary reason for this is that the heat generated by plastic is several times greater than that of metal, and the temperature difference between processing and use of the part results in dimensional variations. Also, unlike metal, the blades used are not as hard, so care must be taken to avoid blade chatter.
Metal can generally be toleranced to 1/1000 mm, but plastic is difficult to tolerate, and the limit is in the 1/100 mm range.
The tolerances in the 1/1000 mm range (h7,H7) for hole and fit tolerances are often seen in drawings from designers and developers. Since these tolerances are impossible to manufacture with plastic, we will always have a meeting to confirm them, but in general, we would like you to use the middle level of JIS as a guide.
Among plastics, there are cases in which dimensional variations become large depending on external factors such as temperature and humidity.
For example, MC nylon has a higher water absorption rate than other plastics, and there have been cases where dimensions have changed by more than ±0.5 mm between dry and rainy seasons. Even if the dimensions are as shown in the drawings at the time of processing, care must be taken when the product is delivered in an environment with different humidity and temperature.
