Experience talk: chrome plating of porous complex parts

The main body of the high-end bathroom faucet series is basically composed of die-cast brass parts and part of zinc alloy. Its surface treatment usually adopts electroplating decorative chromium process.

Most of these high-end bathroom faucets made of die-cast brass are porous and complex parts. When chromium is fitted, there is a large yellow exposed area at the hole position, and it is difficult to install chromium in the low current density area (or welding part).

In the production practice of electroplating decorative chromium for high-end bathroom porous complex parts, the author used plugging technology and improved auxiliary anode design to solve these problems. The bits and pieces of experience in practice are now for my colleagues’ reference.

1 plugging hole

Because of chrome platingThe liquid has the problems of low current efficiency, poor dispersion ability and poor covering ability. Therefore, when electroplating decorative chromium, it is impossible to uniformly plate the chromium coating on the parts with complex shapes, and it is more difficult for workpieces with porous positions.

At present, many electroplating enterprises use rare earth additive chromium plating to improve the coverage and dispersion ability of chromium plating; while enterprises that do not have the conditions to use rare earth additives can determine the mass concentration of CrO3, ρ(CrO3) /ρ(SO2 4-), plating Liquid temperature, current density, etc. are adjusted, but the increase is not large.

For the chromium plating of porous and complex parts, there are usually more plugging techniques used in functional hard chromium plating, and most of them use lead (skin or wire) to plug the holes; however, it is difficult for decorative chromium plating. If the hole is not plugged, the place is exposed to yellow and no chromium is plated.

The author uses plugging technology in the production of electroplating high-end bathroom faucets.

One is to filter the plating solution and soak it with a large piece of white filter paper, then knead it into a paper ball to block the hole. Because the paper mass absorbs a small amount of chromium plating solution during chromium plating, the plating solution is lost, and the waste paper should be treated intensively after use. This method is not advisable.

The second is to use different sizes of white transparent or black hollow soft plastic pipes to plug the holes, but the plastic pipes must be acid and alkali resistant and high temperature resistant.

This method is more scientific, and it is also suitable for chromium coating. Various grades of high temperature acid and alkali resistant tapes, silicon caps, silicon plugs, cork plugs, hollow cone plugs, flangeless silicon plugs, blind hole/threaded hole shielding silicon plugs, straight drawing Series products such as rubber plugs and double-washer pull rubber plugs will become “experts” for electroplating plugging.

2Improving the design of decorative chromium auxiliary anode

When the complex parts of the bathroom are electroplated with decorative chrome, the hole position is exposed by the plugging technology. However, the partial welding parts and low current density parts on the workpiece cannot be plated with chromium, which is another problem.

The author quoted two electrodes on the chrome-plated hanger, one is the cathode, and the middle is separated by an insulating plate; the other is also on the hanger as the anode. The anode wire has two ends. One end is connected to the 8# fuse, which bypasses the hanger to make a ring-shaped auxiliary anode, and the other end of the wire is connected with a stainless steel clip.

Before chrome plating, the auxiliary anode position of the lead fuse should be separated from the cathode. When chrome plating, the tank is charged and the cathode is hung first, and then the stainless steel clip at the other end of the wire is immediately clamped on the anode bar, the current is increased, and the secondary impact chrome plating is adopted.

When the plating time is up, reduce the current when starting the tank, first take the large anode clamp, and then take out the hanger. Wear thick rubber gloves during operation to prevent burns to your hands. In this way, the author solved the difficult problem of complicated bathroom fittings with chromium.

After years of production practice, the author believes that electroplating process< /strong>Although it has its limitations, we can improve it by changing external factors, and perhaps we can achieve a satisfactory plating effect.