Q&A
Knowledge of electroplating and surface treatment
What is surface treatment?
In order to make the product more beautiful, durable, corrosion-resistant, or in order to make it have a certain function, the general term of the processing method taken on the surface of the product, called surface treatment.
Surface treatment of hardware:
The hardware materials of our products mainly include: iron, copper, aluminum, zinc, non-stiff steel, etc., due to different physical properties, the treatment is slightly different.
There are four main types: (1) electroplating, (2) anodic treatment, (3) adding resin, and (4) direct treatment of substrates.
(1) Electroplating:
What is electroplating? It is the use of electrolytes to coat one metal over another.
(2) Anode treatment:
Anodizing is usually only for aluminum, but die-cast aluminum cannot be anodized.
(3) Add resin:
Painting: Pre-treatment--- painting --- drying
Paint: pre-treatment--- spray paint--- baking and drying --- nickel frame (high temperature requirements, different types of paint)
Electrophoretic coating: Pre-treatment--- electrophoretic deposition--- drying
Powder coating: baking --- dipping
(4) Direct treatment of substrates:
Mechanical grinding: grinding. Vibration (coarse. Zhenyou)
Manual grinding: sand wheel (sand belt), hemp wheel, cloth wheel
Sand blasting: Sand particles are evenly sprayed on the surface of the product and shaped to create a rough effect
Dyeing black: Dye black directly, e.g. screws
Phosphating treatment: by phosphide solution (angle steel)
Frozen color: potassium dichromate solution (anti-rust)
Thermal treatment: The product is heated at high temperature and then cooled to change the direction of atomic arrangement
Hardening: carburizing. Add manganese. Quenching
Annealing: Slow cooling
The basic steps of electroplating:
(1) Pretreatment--- (2) Copper bottom--- (3) Nickel plating--- (4) Other color plating --- (5) Sealing oil
(1) Pretreatment: to clean the substrate to make its surface smooth and clean, and enhance the surface activity. Generally, small products are usually put into vibrating
In the moving device, add detergent and degreaser to roll, and then rinse it clean
Often directly degreased to remove the oil, and then clean with water or pure water, if the product is raw or sticky, must
It must be cleaned with sulfuric acid, commonly known as pickling. The pre-treatment of zinc alloy plating must be vibrated and polished manually
The product must be cleaned with ultrasound.
(2) Hit the copper bottom: the copper bottom is divided into red copper bottom and bronze bottom, and in order to make the product brighter when hanging plating, some products must be persulfuric acid
Copper.
(3) Nickel plating: The main metal block in the plating tank is nickel plate, and the main components of the solution are nickel sulfate, nickel chloride, and gloss agent.
(4) Plating other colors: black nickel, bronze, pearl nickel, gold, chrome and other colors.
(5) Upper sealing oil (nickel spray frame) (commonly known as eating and pulling embarrassment): it can isolate the air and supplement the pinhole. Distinguish bright oil from mist oil, acid-resistant oil and many other types of ordinary oil. Note that it is easy to color when the oil is too thin, easy to bloom if it is too thick, and easy to bloom if it is too long to bake Yellow.
The electroplating of hardware is mainly divided into two categories:
(1) Nickel-based plating
(2) Nickel-free plating (non-toxic plating)
The main colors of nickel electroplating are divided into:
(1) Basic color: nickel, zinc, gold, silver, red copper, bronze, black nickel
(2) Synthetic color: pearl nickel, water mist, sand electric black, pearl gold, sand electric gold, sand electric bronze
(3) Processing color: green bronze, black bronze, red bronze, silver, dyeing
Examples of plating color processing:
For example: (1) Sand electricity does not need nickel plating, and directly red copper ---- sand electricity
(2) Green bronze does not need to be nickel-plated, and the bronze ---- directly blackened ---- processed
(3) Zinc color does not need to be nickel plating, direct zinc plating (blue zinc. White zinc. Colorful zinc. Black Zinc)
Please refer to the table below:
Chrome bronze, black nickel, pure gold, pearl nickel, water mist, green bronze, black bronze, red bronze, ancient silver, dyed
Nickel sand electric blackened black
Copper, bronze, zinc
Substrate (iron, copper, zinc or other materials...).
What is the difference between rolling power and hanging power?
(1) Barrel plating:
Put the electroplated workpiece that has been treated before electroplating into the drum, and then immerse the drum in the electroplating bath.
The rolling of the barrel allows the workpieces in the barrel to undergo electroplating treatment, so it is called "rolling electroplating". Rolling electricity is mainly targeted at smaller sizes
Workpieces, such as clothing buttons and a series of accessories, but the effect of rolling electricity will vary slightly depending on the number of workpieces.
(2) Rack plating:
Hanging is to hang the electroplated workpiece that has been treated before electroplating on a suitable rack, and then put the rack into the electroplating bath.
tank for electroplating. The main purpose of hanging electricity is for buckles, hardware and gold-type workpieces, as well as some workpieces that require electroplating effects.
Ask for a higher original. The requirements for the number of original parts in the hook-up are relatively loose, and the deviation caused by the quantity is also small.
The process and principle of rack plating (rack plating) and barrel plating (general electroplating) are the same, but the process level is higher. Because they need to be racked one by one, which is more time-consuming and labor-intensive, so the unit price of rack plating is higher.
Types of defective products for electroplating:
1. Material blistering: The main reason is that the material contains impurities, insufficient density, etc.
2. Electroplating blistering: There are many possible reasons, and the following reasons will cause blistering
(1) Improper preparation of electroplating solution
(2) Improper specific gravity of catalyst (sodium cyanide)
(3) The surface is not clean
(4) The red copper is not polished well
(5) The baking temperature is too high
3. Cai Cai: Caused by the sealing oil being too thin (the oil can be re-sealed)
4. Burning: the current is too strong locally and the product is too thin
5. Surface oil stains: If the sealing oil is too thick, or it has been moved before drying, it will cause surface oil stains.
6. Sandhole phenomenon: Metal is composed of atoms and molecules, which are not arranged neatly and have gaps to form pinholes (density is not enough)
Electroplating precautions:
(1) Factors affecting electroplating quality: current intensity, solution concentration, number of copper plates and nickel plates.
(2) Black spots will appear on bronze if it is used for a long time.
(3) The longer the sand plating time, the brighter it will be
(4) The longer the pearl nickel is used, the more foggy it becomes.
There may be changes in the actual operation of the electroplating process:
For example:
(1) Sand electric water mist: pre-treatment----bright red copper----water mist (not nickel plated).
(2) Powder mist instead of water mist.
(3) Pure gold plus bronze plating can reduce gold plating time.
(4) The substitute gold can be dyed and oiled with bronze.
(5) Sand power can be plated with powder mist without sand throwing.
(6) Iron: after pre-treatment, nickel plating is done directly without red copper (nail type, wire buckle type, sleeve type).
(7) Modification of electricity: It is usually easy to change electricity (nickel and zinc) without sealing oil, but bronze and pearl nickel are more difficult, and black nickel is even more difficult.
Large, electrical modifications are usually handled in a unified manner. The reason is that denickeling agents, concentrated acid degreasing, etc. are required. In addition, zinc alloy materials
It is easy to foam when the quality is changed.
Electroplating related questions:
(1) Nickel color and pure gold color generally do not use sealing oil, why?
Because the two metal elements are relatively stable and difficult to oxidize, they can be maintained for a long time.
(2) Common processing colors in hanging electricity: green, black nickel, bronze, pure gold and nylon.
(3) The secondary colors in electroplating: white nickel between black nickel, water mist between gun color, that is, two-color plating.
(4) When the product weight is large, barrel plating is more expensive than rack plating.
Nickel-free plating:
(1) What is nickel-free electroplating (non-toxic electroplating)?
In order to reduce the toxicity of nickel to the human body, copper-tin alloy is used instead of nickel plating, which is nickel-free electroplating, also called
Non-toxic plating.
(2) Why is nickel toxic to the human body?
Some people are allergic to nickel, which causes itching and sores on the human body. This phenomenon is poisonous to the human body. none
The steps of nickel electroplating are roughly the same as those of nickel-based electroplating, except that you avoid using nickel-containing solutions, such as nickel sulfate, etc. Nickel plating
The layers are replaced with copper-tin alloy. (Pretreatment—red copper—nickel-free nickel substitute)
Plastic performance treatment:
(1) Vacuum plating
(2)Spray painting
Other surface treatments:
(1)Copper Lassa
(2) Color picture coating process: transfer various natural colors and patterns to the product shell, such as wood grain treatment.
