Introduction to the working principle of the powder metallurgy forming hydraulic press

The powder metallurgy forming hydraulic press is a special equipment that uses a hydraulic system to drive the punch to apply high pressure to the metal powder, so that it can be formed into a specific shape blank in the mold. The following is a brief introduction to the working principle of the powder metallurgy forming hydraulic press compiled by the Jianlong Hydraulic Technology Team for reference!

1. Core working principle

1.1 Loading stage

1.1.1 Powder filling: Metal powder (such as iron powder, copper powder, etc.) is evenly filled into the mold cavity through an automatic powder feeding device or manual method.

1.1.2 Powder property requirements: The powder must have good fluidity and compressibility, and lubricants (such as zinc stearate) are usually added to reduce friction.

1.2 Pressing stage

1.2.1 Hydraulic drive: The hydraulic pump station provides high-pressure oil (pressure can reach 50~800 MPa), pushing the main cylinder piston to drive the upper punch down.

1.2.2 Pressurization method:

1.2.2.1 Unidirectional pressing: only the upper punch moves, suitable for simple-shaped parts (such as gaskets).

1.2.2.2 Bidirectional pressing: the upper and lower punches move synchronously towards each other to improve the density uniformity of parts with large aspect ratio (such as gears).

1.2.2.3 Multidirectional pressing: complex structure forming (such as parts with side holes) is achieved through lateral hydraulic cylinders.

1.2.3 Densification process: powder particles undergo plastic deformation and mechanical meshing under high pressure, and the porosity is significantly reduced (the green density can reach 85%~95% of the theoretical density).

1.3 Holding pressure stage

1.3.1 Pressure maintenance: maintain the peak pressure for several seconds to tens of seconds to reduce the elastic aftereffect (the rebound expansion of the blank after demolding).

1.3.2 Function: improve the dimensional stability of the blank and prevent cracks or delamination.

1.4 Demolding stage

1.4.1 Ejection mechanism: The lower punch or ejector slowly ejects the blank under the action of the auxiliary cylinder to avoid sudden stress release and cracking.

1.4.2 Mold reset: The punch is retracted, and the mold is cleaned and ready for the next cycle.

1.5 Auxiliary system

1.5.1 Hydraulic system: It consists of oil pump, control valve, accumulator, etc. to ensure stable pressure and fast response.

1.5.2 Control system: PLC or CNC controls the pressure curve, speed and holding time to adapt to different materials (such as iron-based, copper-based, and hard alloy).

1.5.3 Safety protection: Overload protection, emergency shutdown and other devices ensure safe operation.

2. Core features

2.1 High-pressure precision control: The hydraulic system can achieve stepless pressure regulation to adapt to the compression characteristics of different powder materials.

2.2 Complex shape adaptation: The forming of special-shaped parts (such as steps and curved surfaces) is achieved through multi-action cylinders.

2.3 Low mold loss: Smooth pressurization reduces mold impact wear and extends life.

3. Typical application examples

3.1 Gear forming: Bidirectional pressing ensures uniform density of the teeth.

3.2 Oil-containing bearings: After pressing, controllable pores are retained for oil immersion.

3.3 Carbide tools: Ultra-high pressure (>500 MPa) ensures the strength of the blank.

Powder metallurgy hydraulic presses convert loose powder into high-precision blanks through a hydraulically driven high-pressure forming process, and are the core equipment in the powder metallurgy industry. Its working principle revolves around "pressurization-pressure holding-demolding", and the key technology lies in pressure control and mold design. In the future, it will develop in the direction of intelligence and high efficiency. For more knowledge sharing/suggestions on powder metallurgy forming processes or the need to purchase high-quality hydraulic presses, please feel free to tell us (you can scan the following WhatsApp QR code), Jianlong Hydraulic Technology will provide you with personalized, customized professional solutions and serve you wholeheartedly.