Disadvantages of powder metallurgy process: overall, there are always pores in the product; 2) The strength of ordinary powder metallurgy products is lower than that of corresponding forgings or castings (about 2% ~ 3% lower); 3) Because the fluidity of powder in the forming process is far less than that of liquid metal, there are certain restrictions on the product structure and shape; 4) The pressure required for press forming is high, so the product is limited by the capacity of press equipment; 5) The cost of die pressing is high, and it is generally only suitable for batch or mass production. Metal powder: the quality of the final product is difficult to control freely; Metal powder is expensive; Powder does not obey the laws of hydraulics, which limits the structure and shape of products. Manufacturing equipment and methods: 1) Presser: expensive powerful press is often used; 2) Die: consumable, with high cost; 3) Sintering furnace; 4) Powder is easy to be oxidized, and mixing takes a long time; 5) The size and shape of products are limited.