Is there a big difference between a cast iron bed and a welded bed, and what should customers choose?

01, 2020

by Oree Laser

At present, the bed of mainstream fiber laser cutter on the market is generally divided into two types: cast iron bed (integrated), welding bed (tube sheet welding). Because the price of laser cutting machine is relatively high, consumers will often be entangled when choosing, for fear that the wrong choice will lead to greater losses.


Some people say that the cast iron bed is chosen because of its high quality and long service life;

Others say that we choose to weld the bed because there are many people using it

.....

So what’s the difference between the two? How should consumers choose?


Cast iron bed


The cast iron bed is habitually called an integral cast iron bed in the industry. It is made of flake graphite cast iron with a minimum tensile strength of 200MPa as the raw material and is cast at a high temperature as a whole. After multiple strict thermal aging and natural aging, it forms a bed body with ultra-high stability.

01 铸铁床身.png

Some readers may not have a special understanding of the raw materials of the laser cutter body, Oreelaser will explain in detail for everyone:


● Concept 


Cast iron is one of the earliest metal materials used in human society. Due to the low cost of early cast iron, the production process is simple and has excellent casting and cutting performance. It is still one of the most important materials in machinery manufacturing.


● Classification


According to the form of carbon in cast iron, cast iron can be divided into 5 categories:

1. White cast iron--without graphite

2. Grey cast iron--flake graphite( the initial raw material for laser cutting machine body, also known as grey iron, referred to as HT)

3. Ductile iron--nodular graphite

4. Compacted graphite iron --vermicular graphite

5. Malleable cast iron--flocculent graphite

 

● Effect of graphite on properties of cast iron


The greater the number of graphite flakes, the larger the size, and the more uneven the distribution, the greater the impact on the mechanical properties. The existence of graphite has little effect on the compressive strength of grey cast iron because the compressive strength is mainly determined by the base structure, so the compressive strength of grey cast iron is similar to that of steel.


● Specially processed HT cast iron bed (HT200)


Because graphite has a great influence on the mechanics of cast iron, further processing is needed. High-temperature heating melts molten iron to precipitate the flake graphite in cast iron. After strict heat treatment, it includes the following three steps: annealing to eliminate internal stress(prevent deformation and cracking and ensure dimensional stability); annealing at high temperature(elimination of white mouth structure and improvement of cutting processability); surface hardening(improving surface hardness, wear-resistance and fatigue strength).


● Advantages of HT200 cast iron bed


After the above treatment, HT has high material stability, which is unmatched by other materials and structures. The use of graphite cast iron as the raw material keeps the accuracy of the machine tool for a long time, unchanged for 50 years.


● What the HT200 cast iron bed can bring to customers


The overall dynamic performance of the laser cutting machine tool is stable, the equipment has good stability, long life, and effectively reduce machining errors caused by bed vibration, reduce material waste, and save direct costs for users.


Welding bed


The laser cutting machine of the tailor-welded structure is welded by steel plates as its name implies. During the welding processing, the local structure of the material changes, and due to the heat and unevenness of the entire component, the material and structural stress are more serious. And it can not be eliminated after strict heat treatment procedures. As a result, during the processing , assembly and use of the machine tool, its linear accuracy will inevitably produce slight fluctuations.

02 焊接床身.png

From the above point of view, if you want higher cutting accuracy, longer service life, and lower long-term production costs, you must choose a cast iron bed; the specific configuration of the bed also needs to be based on your own needs.



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