How Pressure & Temperature Are Used To Alter Metals

Sometimes, traditional forming and melting methods can’t produce the exact parts or materials needed for a particular piece of equipment or structure. This is where powder metallurgy comes in. Isostatic pressing is a process that uses isostatic pressing equipment to apply a mixture of pressure and temperature to pulverize materials into powders. From these powders, super alloys can be made. We also see applications in the additive manufacturing sectors today.

How Isostatic Pressing Works

Using specially designed vessels made by an isostatic press manufacturer, a gas or liquid is utilized to apply pressure on powders placed in elastomeric molds. This compaction happens in hydrostatic conditions — meaning, the pressure, which ranges from 5,000 psi to above 100,000 psi, is applied uniformly throughout the metal powders contained in the mold. 

This process is also called cold isostatic pressing (CIP). It can be used to press a variety of powders — including metals, ceramics, and even plastics. 

CIP can be done either in a wet bag or a dry bag pressing operation. The former entails the use of independent molds. The molds containing the powder materials are submerged in the pressure vessel and removed once the pressing is done. The pressurized and compacted material will then be retrieved from the molds as a unified component. Often other processes are applied to harden or solidify the part being made.

In the dry bag process, the mold is already incorporated into the vessel itself. Instead of retrieving the part after pressing, a special mechanism will be responsible for ejecting the compacted powder from the pressing mold. This method is more efficient when the press is purposely built. 

When the isostatic pressing is performed at a high temperature (typically 2000°C), it is called hot isostatic pressing (HIP). The elevated temperature helps in removing porosity in the part being produced. As porosity decreases, density is effectively increased. This results in a part that has impeccable mechanical properties — one that can retain its shape long after initial pressure was applied. 

Because of these characteristics, HIP is used in various fields. Its application includes pressure sintering of powder often used to create parts for engine turbines and aircraft. Diffusion bonding (used in nuclear fuel assemblies) eliminates casting defects and micro shrinkage and repairs parts damaged by creep or fatigue. 

The Advantage of Isostatic Pressing

Unlike traditional uniaxial presses, isostatic pressing can produce parts that have high densities and typically complicated shapes. With the help of the right isostatic press manufacturer, engineers in various industries can design specific elastomeric molds to achieve the shape that they desire for a specific part. 

Hot isostatic pressing also guarantees the consistency of mechanical properties of the parts being manufactured. HIP improves a part’s impact and tensile strength as well as its ductility. 

ustomers with a large or a complex compacting project can benefit from the cost-effectiveness that isostatic pressing provides. 

The Right Isostatic Press Manufacturer

Fluitron is a premier manufacturer of high quality pressure vessels, including isostatic presses, custom reactor vessels and high pressure gas compressors. Their selection of isostatic presses ranges from simple manual pressing machines to fully automated versions used by toll processors. 

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