Electrochemical plating in plastic mold applications
Since the 20th century, 90 years, the global economic recovery, and showed accelerating growth momentum, the global plastics industry, production and sales has shown a steady growth trend. It is predicted that in 2007 global plastics demand will reach 200 million l million tons in 2020 to reach 300 million 8 million tons. Plastic as a modern socio-economic development as one of the basic materials have been widely applied to various areas of the national economy, and steel, lumber, cement and a material area of the four pillars. Therefore, the study and development of plastic molding technology has important engineering significance. Plastic mold plastic molding equipment important one in plastic products manufacturing process plays an important role, directly affects the quality and performance plastic products. With the plastic mold to the small-scale, precision, diversity and large-scale, complex, sophisticated in the direction of development, the growing complexity of its manufacturing process, the production cycle is long, the production costs are high I. In particular, the majority of precision molds imported from abroad, the price very high, and the standard accessories are few. If early failure, will give companies a significant economic losses. Therefore, a convenient way to much-needed complement to the metal mold up to restore the surface of a good way to die.
In practice, there are several ways to choose from. Using the earlier method is welding process. Welding adhesion is very good, but the welding layer contains a large number of oxides, and the weld is inevitable to generate stress in the metal, resulting in the formation of thermal deformation or cracks. The process is relatively new spark deposition or plasma processing method of this process fast and convenient, can be formed on the surface in the workpiece 2 5.4mm thick metal, alloy, metal oxide or carbide layer. However, this process equipment is expensive, but the general adhesion layer deposition is usually also need to follow-up machining, sedimentary layers usually contain more pores. In recent years there has been a new type of metal deposition technique, commonly used in the processing area of l m2 is about the thickness of sedimentary layers l "m to lmm or so, mainly used in high-quality metal deposition of the occasion required, this method is called electrochemical plating process. a basic principle of the electrochemical plating and characteristics of
1.1 The basic principle of electrochemical plating
This simple process, as in arc welding, as the cathode wire caught in the mold or the machine. Anode wire with cotton or polyester-coated anode connected to the power component was transferred to the appropriate voltage value. Anode pad immersed in a small amount of electrolyte, in the mold surface, moving back and forth, until the formation of an ideal uniform metal deposition layer (Figure 1). In order to monitor the thickness of metal layers, power group also should include an energy meter, electricity meter reading is proportional to the thickness of the metal coating.
1.2 General electrochemical plating process
Electrochemical plating process generally includes plating pretreatment, plating plating plating and post-processing of three parts, each part also contains several working procedure. Operation of the process, each process must immediately after plating rinse.
(1) plating pretreatment
① surface repairs: to be plating on the surface must be smooth, often Sabu, metallographic sand paper grinding.
② Surface cleaning: chemical and mechanical methods of plating the surface of the oil, stain, etc. to clean up.
③ Power Net address: Electric Net deal is the electrolytic degreasing. Brush in any base metals are all using the same kind of degreasing solution, but a different base metals the required voltage and time is not the same as fat. After the surface of the net electricity without oil stain on the good and do not hang Baptist Hydra drops.
④ Activation Treatment: to remove the plating in the fat of the oxide film may be formed after plating the surface and make minor etching and crystal structure of metals present to ensure that metal ions can be in the fresh surface to restore the base surface and with a solid binding matrix to form a good coating strength.
(2) plating Plating
① plating hit bottom: As the coating on the combination of different metals of varying intensity, some of plating layer can not be deposited on steel, so for some special kinds of first plating layer plated hit the bottom as a transition, the thickness of (0.00l ~ 0.01) mm . ② plating coating of work: work coating the surface of the final plating layer, whose role is to meet the surface of the mechanical properties, physical properties and chemical properties, and other special requirements. According to the needs of coating performance, choose a suitable final solution, for example, wear-resistant surface, work the choice of coating of nickel, nickel-tungsten alloy 1. For the corrosion-resistant surface, work surface, the choice of nickel, zinc and so on. Nickel is a mold repair the most common, and its bath shown in Table l.
(3) post-treatment plating
Electroplating plating should be conducted immediately after completion of treatment to remove residual edge plating material.
1.3 characteristics of electrochemical plating.
(1) Equipment characteristics: device's small footprint, light weight, easy to carry, allowing on-site or field operations.
(2) Bath Features: Bath majority of metal organic complex solution, there is considerable in the water solubility, and has good stability. Available in a wide current density and temperature range. It has non-flammable, non-explosive, non-toxic, corrosion is small, little environmental pollution, easy operation and security.
(3) process technology and flexible features, deposition speed, coating variety, combined with high intensity. 2 in the plastic mold of
Electrochemical plating in plastic mold an important application is in the mold surface coated with a layer of thin and uniform gold alloy to prevent the processing of PVC or PVDC is released from the release of hydrochloric acid corrosion, corrosion pits will be produced products surface of drag marks, crow's feet and other defects, and will shorten the life of the mold. At present, ordinary electrochemical plating on the plated side in mold 2.5 "m thick gold alloy. This layer of metal released from the PVC coating to prevent erosion, thus significantly increasing the die life. Electrochemical plating using gold alloys Another advantage is that , when the repair coating, will not need to die down and then one can take to repair it. normally used for polishing the surface of iron or steel wire brush with a soft brush into the mold surface is not smooth like to make the new coating with the mold surface fusion together.
When the molding PET, ABS, PE, PP plastic products, these materials are steel and chromium adhesion. Through the gold alloy plating, so that this material can enhance the plastic mold cavity surface with the separation of roles. As long as the thickness of their gold-plated alloy molding PVC of about half the thickness required, they meet the requirements of anti-adhesion.
Finished in the plastic mold in use and in order to rust and corrosion is usually the work of surface modeling, Tumo oil or grease. If you want to remove rust on the surface of mold, usually in the mold and corrosion pits on the surface leaving traces. This deficiency is for the plastic mold is often fatal. By electrochemical plating, while preserving the surface before the mold can be coated with a layer separated by the thickness of plating interlayer up to 50 m. After the plating compartment, if necessary, can be combined with oil or grease coating, for anti-corrosion, 1 2 m thickness of the coating compartment is sufficient. When you need to use the mold, you can be separated to remove, so that mold forming face to the initial state.
3 Conclusion
Electrochemical plating method in aerospace and marine areas of the application of plastic mold is only a few years ago, but by virtue of its simple operation, easy to use, cost-saving advantages of this technology approach in the plastic mold industry, the rapid application development . Electrochemical plating by virtue of their unique advantages in the plastic mold industry will play an important role, which is mainly reflected in:
(1) has a good social plastic mold manufacturing technology for high, long production cycle, processing and high cost of mold material demand is strong, is extremely valuable. Now a lot of precision plastic molds need to be imported from abroad, costs and expenses are high. If the premature failure abandoned, not only economically wasteful, but also a waste of resources. Electrochemical plating of plastic mold repair or reinforce its surface treatment not only meet industry's needs, you can also save money at the same time can play a role in environmental protection. (2) has an important economic benefits such as St. Louis, a manufacturer produces a kind of symbol TwA plastic cups, these airlines logo printed on the side of the cup. When the engraved mark where electrochemical plating of copper and nickel, and then coated with a layer of nickel-tungsten alloy, the surface of the mold is fixed. Has now produced hundreds of thousands of such devices without the application of more than 20 years of history, and in marked plastic cups. So that you can no longer spend a lot of money to open a set of unmarked plastic cup mold, the company saved a lot of money.
This information comes from 【Wishsino Plastic Injection Molding Company Engineering】
