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Mould Fabrication Forging.

Yutung Industrial Limited | Updated: May 15, 2017

Mould Fabrication Defects in mould manufacturing process and preventive measures

1, forging processing

Mould Fabrication High carbon, high alloy steels are widely used in manufacturing molds. However, the existence of different degrees of this kind of steel component segregation, coarse carbide uneven, uneven tissue and other defects. Selection of high-carbon, high alloy steel manufacturing molds, must adopt a reasonable forging process to shape the module blank, so that the steel can achieve the size of the module blank and specifications, on the one hand, can improve the microstructure and performance of steel.

Mould Fabrication In addition, high carbon, high alloy die steel is poor thermal conductivity, heating speed can not be too fast, and heating to even, in the forging temperature range, should adopt reasonable forging ratio.

2. Machining

Mould Fabrication Die cutting machining should strictly ensure the radius of the transition in size, circular arc and straight line should be smooth. If the mould cutting quality is poor, it may cause the mould damage in the following 3 aspects.

(1) due to improper cutting machining, the sharp corners or corners of the circular radius too small, can cause the mold to produce serious stress concentration.

(2) After cutting the surface is too rough, there may be knife, cracks, incision and other defects, they are both stress concentration point, but also cracks, fatigue cracks or thermal crack initiation ground.

(3) Cutting processing failed to completely, evenly cut off the mold wool in rolling or forging the production of the decarburization layer, it may be in the mold heat treatment to produce uneven hardening layer, resulting in wear resistance.

3. Grinding Machining

Mould Fabrication After quenching and tempering, the mould should be grinding to reduce the surface roughness value. Because the grinding speed is too large, the grinding wheel granularity or poor cooling conditions, and other factors, resulting in the mold surface overheating, resulting in local microstructure change, or caused by surface softening, hardness reduction, or higher residual tensile stress and other phenomena, will reduce the use of the mold to choose the appropriate grinding process parameters to reduce local fever, grinding after possible conditions under the stress treatment, can effectively prevent the emergence of grinding cracks.

Mould Fabrication The measures to prevent grinding overheat and grinding cracks are more, such as: using cutting force of coarse granular grinding wheel or poor bonding grinding wheel, reduce the grinding rate of die; choose the appropriate coolant; tempering grinding stress of 2.5013 million ℃ after grinding is eliminated.

4. EDM

Mould Fabrication Application of EDM machining tooling, discharge area of the current density is very large, produce a lot of heat, mold processing area temperature up to 10,000 ℃ or so, due to high temperature, thermal impact zone of the metallographic microstructure will change, mold surface due to high temperature melting, then cold, quickly solidified, forming a further solidification layer.

Mould Fabrication Under the microscope can be seen, the solidification layer is white bright, there are more microscopic cracks inside. In order to prolong the die life, the following measures can be used: adjusting the electric spark machining parameters or mechanical grinding to grind the surface of EDM after machining, remove the white layer in the abnormal layer, especially to remove the microscopic cracks. Arrange a cryogenic tempering after EDM, stabilize the abnormal layer and prevent microscopic crack propagation.