Precision plastic injection mold tooling is often deformed during heat treatment. In order to prevent this bad phenomenon, the deformation of the mold can be reduced and controlled as long as its deformation law is grasped, its causes is analyzed and the use of different methods for prevention are adopted. In general, the following methods can be used to prevent heat treatment deformation of precision plastic injection mold tooling.
(1) Fair selection of material.
good material of micro-deformation mold steel should be chosen for the precision plastic injection mold tooling, fair cast with the carbide segregation of severe mold steel, solid solution double refinement heat treatment used for the larger and unable to cast mold steel.
(2) Mold structure design should be fair. The thickness should not be too disparate and the shape should be symmetrical. The deformation law should be grasped for larger deformation mold, and machining allowance should be reserved. A modular structure is available for large, precision plastic injection mold tooling.
(3) Preheating should be processed in precision plastic injection mold tooling to eliminate the residual stress generated during the machining process.
(4) Fairness in selecting the heating temperature and controlling the heating speed. For precision plastic injection mold tooling, slow heating, preheating and other balanced heating methods can be used to reduce heat treatment distortion.
(5) Try to use pre-cooling under the condition of guaranteeing the hardness of the mold. The plastic injection mold tooling can be cooled and quenched or warm quenched.
(6) As far as the premises permit, vacuum quenching and sub-zero cooling after quenching are used as much as possible for precision plastic injection mold tooling.
(7) Pre-heat treatment, aging heat treatment, quenching and nitriding heat treatment can be used to control the precision of the mold for some precision and complexity of the mold.
(8) When repairing defects such as holes, porosity, wear and tear of the mold, the cold welding machine and other repair equipment with small thermal influence should be chosen to avoid deformation in the repair process.
There are many ways to operate the heat treatment process, including plugging, strapping, mechanical fixation, appropriate heating methods, accurate selection of the cooling direction of the die and the direction of movement in the cooling medium, etc. A fair tempering process is also an effective measure to reduce the distortion of precision plastic injection mold tooling.