In high pressure aluminum casting, the cylinder and especially the piston are in constant contact with liquid aluminum at about 700oC. The durability of the cylinder and piston is determined by two factors. Therefore, in addition to the requirement of high wear resistance, the part must also avoid sticking to aluminum during casting. The cylinder is usually made of SKD61 steel, rough machined to size and then heat treated to achieve a certain base hardness. After heat treatment, the cylinder is finely machined to size before being nitrided. To ensure the life of the piston and cylinder of the high pressure aluminum casting machine, two main factors are decisive:
- Mechanical processing: cylinders and pistons must be manufactured with precise dimensions. The clearance between the cylinder and piston is a technological secret. In addition, very few units pay attention to the post-nitriding process which affects the size and roughness of the working surface of the piston and cylinder bore.
- Thickness and properties of the absorbent layer: to ensure the thickness of the absorbent layer and the white layer to ensure the life committed to customers.
THT has researched and tested to manufacture cylinders and pistons with a longer life span than the customer’s old products.
Some pictures of our company’s cylinder manufacturing process:
Figure 1. Image of cylinder after mechanical processing
Figure 2. Image after heat treatment
Figure 3. Image of cylinder and piston after grinding before impregnation
Figure 4. Product after nitriding
In addition to the usual blue nitriding mode, THT also provides white nitriding, for beautiful white product surface quality, products are measured and inspected before being delivered to customers.
Figure 6. N-permeable products are tested for hardness before being returned to customers.