Plastic machining in a professional way – Recommendations for action from the plastics turning shop K&B

1. influence plastics already before processing

Solid bodies, which consist of synthetic or semi-synthetic molecule chains in particular, are called plastics in our industry. Properties of the various plastics such as hardness, formability, durability or quality can be determined on the one hand by the material properties and on the other hand by the specific manufacturing processes of our machines. Our plastic blanks are used by our customers as a material for countless applications and products.

2. processing of plastic in comparison with metal

Compared to alternative materials such as metal, our plastics have some advantages with regard to production and usability for various applications. Due to its low strength, plastic is usually at a disadvantage with regard to its mechanical processing possibilities. Even in contact with electricity and heat, metals usually have better properties than plastics. On the other hand, for this reason plastics are preferably used for the production of insulation products. In addition, our plastic products have a lower density than metal and therefore a lower weight as well as better sliding properties. In addition, our products have an enormously high resistance in contact with a variety of chemicals. The production of complex plastic mouldings with high quality is also much easier for us to produce than, for example, the complex casting of metals. For these reasons, our plastics and their professional processing have long been of great importance to our customers. The use of our plastic products is particularly recommended for applications where a good weight/strength ratio is required.

3. types of machining of plastics – our recommendations

The fastest and most economical way to produce complex components is plastic machining, e.g. by CNC milling. Our plastic turning shop K&B can also realize particularly low tolerances and an existing high quality of the material with the help of machining processes. In comparison with alternative materials such as metal, our plastic products are available in a much greater variety and can therefore be used and processed in many more ways.
Plastic machining does not pose any major challenges to our professional processes for machining the material. For the machining of plastics in our industry, machines equipped with HSS (high-performance high-speed cutting steel) or carbide tools for wood and metal processing are now even in use. The plastic turning shop K&B processes its plastic products with the aid of CNC milling, sawing, turning or drilling.
An exception for simple and fast plastic machining is a series of glass fibre reinforced plastics. Although it is basically possible for us to carry out this type of plastic machining using carbide-tipped tools, the products manufactured in this way are comparatively expensive, as the low tool life of the tools makes the manufacturing or machining process less attractive in terms of price. We therefore recommend diamond-tipped tools for the machining of plastic materials with glass fibre components, as these represent a considerably higher cost factor on the one hand, but on the other hand can also withstand longer tool lives and thus meet the requirements.

3.1 Milling

In the field of plastic machining, CNC milling of the material is a popular machining method for us. There are a few things to consider, such as the dissipation of heat via the chip. The heat input into the plastic is significantly influenced by the choice of tool and the cutting parameters. For professional machining centres such as our plastic turning shop, the machining of plastics by CNC milling poses no further difficulties. Through the use of a high cutting speed and a medium feed rate, we achieve excellent performance as well as good material accuracy and surface quality in the machining of plastics. It is also important for our work that the chip space of the CNC milling machines for plastic machining is sufficiently large so that the corresponding chips can be reliably removed and no heat accumulation occurs.

3.2 Sawing

Plastic cutting by sawing is carried out by our teams in contact with band and circular saws. The shape of the semi-finished products determines the selection of the appropriate tool. For the processing of our plastic products, we often use a so-called support groove when using band saws. This allows the cutting of solid rods and tubes, whereby the chamfer ensures that any heat generated can be dissipated via the saw blade. In order to prevent the saw blade from being jammed, we also make sure that there is sufficient setting when cutting plastic. In contrast to the band saw, we usually only use circular saws for cutting plastic panels and blocks with straight cutting edges. When cutting plastic in contact with a circular saw, some aspects must also be taken into account. In order to ensure smooth chip removal and to prevent overheating of the plastics and jamming of the saw blade, we recommend that you set the machine to sufficient feed rates. In addition, when using circular saws for plastic cutting, you should always pay attention to the use of carbide-tipped saw blades.

3.3 Turning

When machining plastic by turning, obstruction of the tools due to flow chips can be prevented by ensuring that the chips are removed smoothly. We also use steady rests, which can be extremely helpful when cutting longer plastic products and otherwise there is a risk of sagging of the material.

3.4. Drilling

As already mentioned, the machining of plastics can also be carried out using conventional HSS drills. In this process, too, we make sure that in contact with a drill, the resulting chips are removed without any problems. If this aspect is not observed, the plastics may overheat too much, especially in deep drill holes on the bore wall, which would result in lubricating the drill. In contact with thin-walled plastic, we also recommend high cutting speeds and the use of a neutral rake angle for optimum machining. In this way, the drill does not hook into the plastics and tearing out or pulling up the plastics on the drill can be prevented.
If you are interested in plastic blanks, do not hesitate to contact us! We will be happy to prepare a non-binding offer for you – tailored to your individual requirements!