Especially for plastics

Applications of plastics are almost unlimited (and unmanageable). They range from a functional part made of plastic to workpieces made of GFRP or CFRP to highly transparent plastic parts for advertising or the optical industries.

TOOLS FOR CNC PLASTIC PROCESSING

OF LETTERS AND HONEYCOMBS

The art of plastics processing

The machining of plastics is one of the major fields of application for CNC machining.

An almost unlimited variety of materials is machined, each with its own specification, special properties and tool requirements.

In principle, however, all plastics have a significantly poorer thermal conductivity than metals, for example, so the heat generated during the machining process must be removed with the chips.

The following types can be distinguished:

Thermosets - Epoxy resins (EP), polyurethanes (PU), formaldehyde resins (PF, MF, MPF, UF) and silicone rubber (SI)
Thermoplastics - Polyolefins (PE, PP, PVC), Styrenics (PS, SAN, ABS, POM), Fluorine-based (PTFE, PVDF), Polyamides (PA), Polyester (PET, PPE, PEEK), Polysulfones, Polycondensates
Elastomers - rubber, latex, caoutchouc
Foams - soft and hard foams made of PE, PU, EPS
Fibre plastics - GFK, CFK, AFU

Fields of application for plastics

Plastics are processed in almost all industrial sectors. Typically, plastic parts are cast or drawn and then reworked. Machining (drilling, milling, reaming and thread cutting) is often used as the machining method.

In this case, cutting tools with extremely sharp cutting edges and extremely smooth surfaces are required so that the plastic can be separated and quickly transported away without great effort. The result is good surfaces on the workpiece and long tool life.

Fibre plastics

Special technical requirements must be observed when machining fibre plastics, composite materials and composites.

Type of fibre
Fiber structure and fiber shape (HT, IM, ...)
Fiber alignment (UD / MD,
Matrix (Tg: glass transition temperature)
Thickness (vibration, clamping)
surface treatment
Fillers (Honeycomb, Foams)

These are very different in the individual case. We will be happy to support you with technical advice on milling, drilling and thread cutting for your plastic application.

On request, we will analyse the requirements in your company and develop a suitable solution for you - with tools that are specially tailored to your machine and your application.

PROCESSING INSTRUCTIONS

1. secure clamping

The plastic should be as stress-free as possible during clamping in order to obtain finished parts that are as stress-free as possible. In some cases, the workpieces are quite large, so that vacuum clamping is necessary.

2. Extremely sharp cutting edges

Tools for plastics processing should have a large cutting angle and be extremely sharp. Machining very soft plastics in particular is only possible with extremely sharp tools.

3. polished flutes and cutting edges

Polished flutes on the drill or milling cutter facilitate the fast and clean removal of the plastic chips. This prevents the still hot chips from compacting again and sticking to the tool.

4. Correct cutting values

Milling or drilling generates temperatures that melt the plastic or heat it to such an extent that its structure is damaged. Therefore, when machining plastics, high feed rates must be observed in comparison to the (relatively low) speed. The material is quickly cut and transported away, it takes the heat with it and there is no thermal damage.

5. coolant

Whether coolant can be used often depends on the production specifications of the end user and the plastic used. If coolant is permitted, the plastic can be cooled during machining to reduce heat generation. If a coolant is not permitted or possible, heat can be removed from the machining process with compressed air or cooled compressed air.

6. deburring afterwards

When processing plastic parts, sharp edges often occur. These must be removed before further use to avoid injury or damage. You will find the appropriate machine deburring solutions with our multifunctional tools.

Material

Duroplast

After hardening, they can no longer be plastically deformed. They burn when reheated. They are resistant to solvents and have no tendency to swell or creep.
Thermosets are used in the manufacture of car bodies and structural parts. In addition, the matrix of most fibre plastics (CFRP, GFRP) consists of thermosets.

The most important groups within thermosets are epoxy resins (EP) and polyurethanes (PU), supplemented by formaldehyde resins (PF, MF, MPF, UF) and silicone rubber (SI). In the processing of thermoplastics, it is essential to keep the temperature in the process low in order to avoid thermal damage during machining.

-> SPPW Rapid-Line cutters for plastics have particularly sharp sheaths and a polished surface. This enables high feed rates and clean cutting edges without burr formation.

Material

ThermoplastE

They return to their original shape after heating (cooling). They have many design advantages due to their permanent formability and are therefore widely used.
Frequent plastics in this group are: Polyolefins (PE, PP, PVC), styrenes (PS, SAN, ABS, POM), fluorine-based (PTFE, PVDF), polyamides (PA), polyesters (PET, PPE, PEEK), polysulfones, polycondensates, etc.
When processing thermoplastics, it is crucial to keep the temperature in the process as low as possible in order to avoid deformation during machining.

-> SPPW Rapid-Line cutters for plastics have particularly sharp sheaths and a polished surface. This enables high feed rates and clean cutting edges without burr formation.

Material

CFRP - "Carbon"

Carbon fibre (reinforced) plastic, consists of the C-fibre and the plastic matrix, mostly epoxy resin.
The properties of matrix and fiber complement each other. Machining by breaking the fibres. Heat is a problem because the matrix can degenerate. There is also a risk that CFRP will delaminate.

-> SPPW CFRP milling cutters have many cutting edges with chip breakers and are coated with Dia.HC or diamond.
Cutters with alternating spiral direction avoid delamination.

Material

GFRP - Glas fibre

Glass fibre (reinforced) plastic, consists of the G-fibre and the plastic matrix, often epoxy resin. GRP is a low-cost fibre composite material. Large parts can be produced without any problems.
Depending on the production method, the fibres are often random. Aligned GRP laminates or combinations with other chamfers also occur.

-> SPPW GRP cutters have a pyramid-shaped toothed cutting edge and are often coated with Dia.HC. The cutting edges are available in fine, medium and coarse profile shapes as well as different face geometries for the respective application.

Material

AFK - ARAMID FIBRE PLASTIC

Aramide (known as Kevlar®) are textile fibers used to reinforce plastic parts, often as protection against heat. Very often they are also used as ballistic protection (protection against fire) in protective vests, helmets and military vehicles. Aramid is also used in racing to reinforce structural components. AFK is extremely tear resistant. However, the fibres tend to splice during cutting. They must therefore be machined with particularly sharp tools.

-> SPPW aramid milling cutters have an extremely sharp cutting edge and an alternating spiral direction. They create a counter-support in the rotation which makes it impossible for the textile fibre to bend and escape the cutting edge. The result is a smooth cut without any fibre projection.

Material

TRANSPARENT PLASTIC

Particularly in the optical industry and display construction, very high demands are placed on the transparency of the processed surfaces. These often have to be "highly transparent", which is very often associated with manual post-processing or additional work steps.

-> SPPW Rapid Shine milling cutters, with their highly polished surface and special cutting edge geometry in conjunction with cutting speeds (vc 300-500m/min), enable virtually crystal-clear and burr-free milling of transparent surfaces.

Material

FOAM MATERIALS

The applications of foams are manifold - as fillers for stiffening components, as protection or padding for storage and sorting, or in orthopaedics for padding in insoles.
Depending on the application, the base material and the air content of the foam vary greatly. This results in very different demands on the tools. What the applications have in common, however, is that very long tools are almost always required.

-> SPPW foam milling cutters are available in two basic versions: Cutters (with face radius) for copying hard foams with pyramid toothing and cutters with flat spiral and polished flute for optimum, fast chip removal when milling deep 2.5D grooves in soft and medium-hard foams.

Material

Honeycomb (Wabenverbund)

Honeycomb composites (WV) are used to improve (or enable) the structural strength of large components with the aim of reducing weight compared to solid materials.
Common honeycomb composites are aluminium, glass-based or aramid-based fibre plastics. Special forms made of paper can be found as well as those based on titanium.
Machining with normal tools is not possible because the honeycombs are pressed down and cannot be cut. Remains of the honeycomb remain, which have to be removed by hand.

-> SPPW Honeycomb milling cutters, also known as choppers or hoggers, have an extremely large number of small, spiky blades that divide the honeycomb structure and then peel it off.
The cutters are partly combined with a peeling knife at the forehead.

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