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Composites cutting via CNC cutting machines

CNC cutting machines are generally associated with metal parts tooling…or eventually with stone parts tooling. However, two cutting technologies - waterjet cutting and laser cutting allow tooling of more kinds of materials. Interesting example are plastics. They are used in industry more and more often, mainly because of their features. Very desirable are materials which keep high strength level but still stay light and flexible. What are they in tooling process? Is it possible to cut them alike? For presenting problem interestly, there are submitted few examples of composite materials below.

What are composite materials? It is worth to get more knowledge about this topic because since last 10 years there has been constant growth of their utilization in many new projects. This concept is often associated with aeroplanes, timber, military equipment or sport equipment. Meanwhile, name “composite” can mean huge group of materials with inhomogeneous structure which is built by minimum two components. Mostly one of them is binder for whole material and it ensures of its physical features. Components can be braided together or layered.

Known example of composite material that we meet every day is reinforced concrete. It consists of compressed concrete with metal elements. In this case concrete is binder that makes material more durable.

Generally, composites can be split into two groups: laminates, structural composites, microcomposites and nanocomposites. Their features decide about difficulty tooling level. Especially they can be hard like steel or flexible like gum and they also keep resistance to high stresses.
If you try to cut composite materials unsuitable methods, you can bring it to structure delaminating. It significantly reduces utility material possibilities, especially in fields like aircraft or medicine where details are the most important.

In case of shortbread materials, waterjet cutting is recommended . Main reason is of course ecology due this is always the most optimal method. However, in case of waterjet cutting specifics for composites cutting, unmistakable advantage is uniquely high cutting quality because there aren’t burrs created which should be additionally leveled. There is also no heat impact zone (temperature is not higher than 40°) or impact of chemical substances, therefore there is no change of material structures.

Preparing for process is in this case reduced to correct cutting programming. That makes process really easier. Cutting process takes place without redundant demurrages (for example for replacing of consumable parts or cutting head). There is also no need to sharpen cutting tools. Besides, this technology doesn’t need earlier drills - material can be directly pierced. Depends on needs, there is possibility to adjust water stream power.

Waterjet technology limits are not plain surfaces. Difficulties can also appear if very soft material is mixed with harder material. If it is possible, you should place harder material on top. In inversely situation, water stream after soft part piercing, it bounces off from harder part and destroys soft material.
As mentioned before,waterjet cutting is especially recommended for fragile materials. But how is it in other cases? There is risk of destroying edges by abrasive or their dampness. During cutting of composites with carbon fiber, there is risk of detachment of fibers from matrix.

For this kind of problems avoiding, it is worth to choose laser cutting. Its main advantage is access for whole material. Besides, laser cutting is not limited because surface or shape of material. But it is necessary to remember that this technology is suitable only for materials from 1-8 mm thickness. Probably in nearest future laser technology will be known as standard tool for most of composite materials cutting (strengthened by fiber). Arguments are the same like in case of plates. The most encouraging factors are: process speed, no friction and contactless work. Important is also lack of limit for geometry or surface.

For summary, there is table below. In table you can see information about composites cutting aspects in three technologies: waterjet cutting, laser cutting and plasma cutting.

ParameterWaterjet cuttingLaser cuttingPlasma cutting
Non-metallic materials+++
Multilayer cutting+++
Composite materials+++
Curing the material---
Burr formation---
Additional machining---
Formation of poisonous fumes---
Material deformation---

According table above, waterjet cutting is the most optimal technology. If water influence is not destructive for cut plastic material features, there is waterjet cutting the most suitable way. It worth to follow new plastics usage and their features. It can come to be perfect idea for using of CNC cutting machines.