The mold material is mold manufacturing material and technological foundation. The steel mold is the traditional mold materials, varieties and specifications, quality and performance of the service life of the mold manufacturing cycle and plays a decisive role. The control is based on the domestic and foreign brands of die steel die steel of different needs, in the same class of steel at home and abroad and the classification of different naming, greatly improving the application efficiency of die steel in recent years, domestic and foreign steel mold production, production technology, technical equipment, quality, variety and other aspects have made development rapidly. Domestic enterprises also produced a number of high-quality platform. Objective to promote the popularity of foreign brands in the domestic market and steel, die steel grades comparison also came into being.
Selection of molding parts materials
.1 refers to the direct contact with the plastic molding parts and molding mold parts, such as cavity, core, slide, insert, inclined top, side drawing etc..
.2 molding parts of the material is directly related to the quality and life of the mold, determined by molding plastic products, appearance and quality, must be very careful, generally based on the provisions of the contract and customer requirements, selected according to the requirements and characteristics of products and molds.
The selection principle of the.3 parts of the molding material are: according to the molding of plastic type, product shape, size precision, the appearance of the product quality and service requirements, production batch size, taking into account the performance of the material cutting, polishing, welding, etch, deformation, wear, considering the condition of economy and mold manufacturing and the processing method, to choose different types of steel.
.4 for forming transparent plastic products mold, high-grade steel imports the cavity and core are made of high performance mirror polishing, such as 718 (P20+Ni), NAK80 (P21), S136 (420), H13 steel, 718, NAK80 for the pre hardened state, did not need to heat treatment; S136 and H13 steel were annealed, the hardness is HB160-200, after the rough machining of vacuum quenching and tempering process, the hardness of S136 is HRC40-50, H13 type steel, the hardness of the general HRC45-55 (according to the specific grade determination).
.5 for the appearance of product quality requirements, mold longevity, mass production, and the molding parts material selection are as follows:
A) high-grade imported steel cavity to be high mirror polishing performance, such as 718 (P20+Ni), NAK80 (P21), are pre hardened state, without heat treatment.
B) core can be used in low-grade imported P20 or P20+Ni steel, such as 618, 738, 2738, 638, 318 and so on, are pre hardened state; mold of small batch production, can also be used for domestic plastic mold steel or S50C, S55C and other imported high-quality carbon steel.
.6 for general appearance and the quality of the product requirements of the mold, the molding parts material selection are as follows:
A) small, precision mould cavity and core are made of imported P20 or P20+Ni steel grade.
B) of large and medium sized mold, the plastic molding has no special requirements on steel, the cavity can be used in low-grade imported P20 or P20+Ni steel; core can use low-grade imported or imported high-quality carbon steel P20 steel S50C, S55C etc., can also be used for domestic plastic mold steel.
C) for cavity corrosion striae, when corrosion should strive to avoid pear pattern selection of P20+Ni class of 2738 grade (738).
.7 on appearance quality requirements of the internal structure, the molding material has no special requirements on steel, the forming parts material selection are as follows:
A) for large and medium-sized mold, imported P20 or P20+Ni steel cavity can be used low, can also be imported high quality carbon steel S55C, S50C or P20 domestic or P20+Ni plastic die steel; core can use imported or domestic high-quality carbon steel.
B) for small die, if high yield, complex structure, import P20 or P20+Ni steel cavity can be used low, also can choose the domestic P20 or P20+Ni plastic die steel; core can be domestic plastic mould steel.
For C) has the advantages of simple structure, small mold production is not high, core and cavity can be used for domestic plastic mold steel or carbon steel.
.8 plastic mold corrosion and all kinds of flame retardant plastics for molding containing fluorine, chlorine, if the product requires high corrosion resistant steel can be used to import, the general requirements of the choice of corrosion resistant steel made in china.
.9 for die forming strong friction impact plastic for steel, such as injection molding Nylon + glass fiber material, should be used with imported high abrasion resistance and high tensile strength and high toughness thermal advantages or domestic H13 class steel.
.10 insert molding general and inserted into parts with same material. For high or require the cooling effect of the mold is difficult to cooling a portion of the insert material should be selected in beryllium or aluminum alloy.
.11 for moving parts in the mold molding materials involved in the selection principles are as follows:
A) transparent parts should be the choice of high-grade imported steel polishing is good, such as 718, NAK80 etc..
B) non transparent, generally mid-range imported steel used hardness and high strength, such as 618, 738, 2738, 638, 318, surface nitriding, nitriding depth is 0.15-0.2mm, hardness is HV700-900.
C) if the mold requirement is low, can also use low-grade steel imports or domestic steel, nitriding hardness is HV600-800.
Selection of non molding parts and materials
According to the.1 standard mold mold materials, templates imported or domestic SM45 S50C, HB160-200, uniform hardness, and the internal stress is small, not easy to deformation. The guide column is made of GCr15 or SUJ2, hardness is HRC56-62. The push plate guide pin, the push plate guide sleeve and a reset rod material can be used GCr15 or SUJ2 guide, and the hardness is HRC56-62; also can be used T8A, T10A, hardness is HRC52-56.
The general structure of.2 in mold parts, such as the top of the positioning ring, column, top limit block, limiting pull rod, a lock module, no special requirements on the hardness and wear resistance, can be domestic SM45 steel, normalizing, hardness HB160-200, without heat treatment.
.3 in the mold gate set, the wedge block, wear block, press plate on the hardness, strength and wear resistance requirements of the higher parts, should use carbon tool steel and high quality carbon tool steel, such as T8A, T10A etc.. This kind of steel is used for quenching treatment, in order to improve the hardness and wear resistance.
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