Plastic Electroplating Range:
ABS Plastics are usually used for electroplating of plastic parts.The general procedures are degreasing, roughening, sensitization, activation,
electroless nickel plating or electroless copper plating,thickening of copper plating,and surface layer plating.The surface layer generally includes nickel,chromium,imitation gold,etc.,depending on needs.
Electroplating process:
1.Cleaning: To remove the dirt and fingerprints left during the plastic molding process,it can be washed with an alkali agent,then neutralized with acid immersion and washed with water.
2.Solvent treatment: Wetting the surface of the plastic to interact with the conditioner in the next step.
3.Conditioning: The surface of the plastic is roughened into internally locked cavities to make the plating layer close and not easy to peel off,also known as chemical roughening.
4.Sensitization: Adsorb the reducing agent on the surface,commonly used(stannous chloride) or other tin compounds,that is,sn ions are adsorbed on the plastic surface and have a reducing surface.
Advantages of plastic plating:
1.Easy to shape and good shape.
2.Light weight.
3.Good corrosion resistance.
4.Good drug resistance.
5.Excellent electrical insulation.
6.Low price.
7.Can be mass produced.
Disadvantages of plastic plating:
1. Poor weather resistance,easy to be embrittled by light.
2. The heat resistance is not good.
3. The mechanical strength is small.
4. Poor wear resistance.
5. High water absorption rate.
Plastic Electroplating Mold Design:
In order to ensure that there is no defect on the surface of the plastic plating part,no obvious directional structure and internal stress,the following requirements should be met when designing and manufacturing the mold.
1. The mold material should not be made of beryllium bronze alloy.It should be made of high-quality vacuum cast steel.The surface of the cavity should be polished to a mirror-brightness along the mold ejection direction,and the unevenness should be less than 0.2mm.The surface is best plated with hard chrome.
2. The surface of the plastic part faithfully reflects the surface of the mold cavity,so the mold cavity of the electroplated plastic part should be very smooth,and the surface roughness of the mold cavity should be 1 to 2 levels higher than the surface roughness of the part.
3. Parting surface,weld line and core inlay line cannot be designed on the plating surface.
4. The gate should be designed at the thickest part of the part.In order to prevent the melt from cooling too fast when filling the mold cavity,the gate should be as large as possible(about 10% larger than the ordinary injection mold).It is best to use a gate and runner with a circular cross section,and the length of the runner should be shorter.
5. Exhaust holes should be reserved to avoid defects such as air filaments and air bubbles on the surface of the workpiece.
6. When selecting the ejector mechanism,ensure the smooth demolding of the part.
ABS Platic is one of the most widely used in plastic electroplating.ABS Plastic is a terpolymer of acrylonitrile(A),butadiene(B) and styrene(S).For electroplating grade ABS Plastics,the content of butadiene has a great influence on electroplating,and should generally be controlled at 18% to 23%.High butadiene content,good fluidity,easy to shape,and good adhesion to the coating.Since ABS is a non-conductor,a conductive layer must be attached before electroplating.
Molding:
Injection molded parts inevitably have internal stress due to the characteristics of the molding process,but proper control of the process conditions will reduce the internal stress of the plastic parts to a inimum and ensure the normal use of the parts.On the contrary,if the process is not properly controlled,there will be a lot of internal stress on the part,which will not only reduce the strength of the part,but also warp and deform or even crack during storage and use,which will cause the coating to crack or even fall off.Therefore,the control of process parameters should make the internal stress of the part as small as possible.The process conditions to be controlled include raw material drying,mold temperature,processing temperature,injection speed,injection time,injection pressure,holding pressure,holding time,cooling time,etc.
Post-sculpting treatment:
Due to injection molding conditions,injection machine selection,part design and mold design,internal stresses exist in different parts of the plastic parts to varying degrees,which will cause insufficient local coarsening,difficult activation and metallization,and ultimately lead to metal the chemical layer is not resistant to collision and decreased bonding strength.Tests show that both heat treatment and surface finishing agent treatment can effectively reduce and eliminate the internal stress of the plastic parts,and increase the bonding force of the coating by 20-60%.
In addition,the molded plastic parts should be specially packaged and isolated,and it is strictly prohibited to scratch or scratch the surface,so as not to affect the appearance of electroplating.During the inspection,the inspector should wear degreasing gloves to prevent contamination of the surface of the plated parts and affect the adhesion of the coating.
