From the beginning of the design to the finished product, the powder metallurgy parts are processed through a series of processes to the finished product, and the numerical value often changes in the process. Because the size and shape of the powder metallurgy structural parts are generated by the metal powder pressing to sintering process, in order to obtain satisfactory material density and mechanical properties, the parts are pressed and formed under a given pressure, so the actual part size is mainly controlled by the capacity of the used press. Powder metallurgy pressing is not suitable for making long parts, because the density along the length of the part will be different, and the density will be slightly smaller at the side of the mold.

The shapes easily made by powder metallurgy process are parts with the same size in the pressing direction, which are especially suitable for making cams, gears and those with concave convex shape.

In the production of powder metallurgy structural parts, the single axial rigid die is usually used for pressing, that is, only the axial pressure is applied, and the part compacts must be separated from the die in the axial direction. Therefore, the following shall be considered when evaluating whether the parts are suitable for powder metallurgy production:

(1) The shape of the part must be easy to load powder

The shape design of powder metallurgy parts should be conducive to the powder loading of the die and the powder flow to fill the cavity during the compaction process. However, the flow behavior of metal powder is far inferior to that of liquid, so the shape design of parts should be conducive to powder flow to effectively fill the mold cavity. Prevent insufficient powder loading in some parts, forming low density areas, reducing green strength and mechanical properties of sintered parts, and distorting deformation during sintering. Low green strength may also lead to spalling and cracking.

(2) Part structure with sharp corners

When parts with sharp corners are filled with powder, if more powder is filled but cannot be discharged, it is easy to split the mold support. If parts with sharp corners are filled with less powder, a low-density area will be formed. Therefore, if you want to achieve the same density of parts, you must ensure that the pressure and powder filling are uniform.

(3) If there is structure in the internal space of components

There is interlayer in the part, and powder metallurgy pressing is not easy to complete, because it is pressed and formed in a single axial rigid mold, and the internal structure cannot be pressed. If the iron powder is pressed in, it cannot be taken out of the mold. Therefore, the component shape is limited.

(4) Limitations on the strong solidity of the die

The shape of the part shall be conducive to the solidity of the die and high production efficiency. Thin sections in the die can cause fracture and wear of the die and should be avoided.

(5) No more than four product countertops

Parts with more than four worktops are not suitable for conventional powder metallurgy pressing. Since the worktops of parts are formed by independent upper and lower die punches, if powder metallurgy requires density, die punches should be as few as possible, because uniform density of pressed blanks is important for increasing and stabilizing the strength and dimensional accuracy of powder metallurgy structures. Or the die punching is reduced, that is, the worktable of parts is reduced, and the worktable will be processed later.

In addition, when the requirements for parts are not so strict, multiple parallel worktops can be pressed on a die punch. In short, the product density is uneven.

(6) Component Size

Different presses are selected for the size of parts and components. At present, the press coverage tonnage of Lianyungang Fuchi Intelligent Manufacturing Technology Co., Ltd. is 40-800T. For example, if the force bearing area of parts is too large and there are many worktops, the 800T press may not be able to produce due to limited pressure.