Posted on 2018-09-17 Dacromet coating process: the raw material is formulated into a water-soluble coating, and then coated on the surface of the pre-treated workpiece, pre-baked and sintered to form an inorganic film layer. The basic process is as follows: workpiece degreasing → derusting (blasting) → dip coating (or spraying) → drying → pre-baking → sintering → cooling → inspection → packaging.
1. Degreasing: Degreasing organic solvent or alkaline solution deoiling. From the perspective of environmental protection, alkaline degreasing should be used. After the degreased workpiece, the surface is required to be wetted by water.
The workpiece is placed in a closed container, and the cleaning agent is introduced at a high pressure and sprayed for cleaning. Since the surface of the workpiece is a mineral anti-rust oil, a compound surfactant having an emulsified dispersion and a good dissolving power is selected.
2. Shot blasting: In order to avoid hydrogen embrittlement and environmental pollution, rusting is not used for pickling, but shot blasting is used. The steel shot peening machine used in the shot blasting machine has a diameter ranging from 0.1 to 0.6 mm, and is dusted by compressed air. The removed dust is collected by a special dust collector and concentrated. Degreasing and descaling must be thorough, otherwise the adhesion and corrosion resistance of the coating will be reduced.
3. Dip coating: The treated workpiece is immersed in a pre-formulated Dacromet coating solution. The workpiece is typically dip coated for 2 to 3 minutes under slight shaking and then dried. If the workpiece is large, spray it. After dip coating or spraying, if there is unevenness or leakage coating after inspection, it can be applied by brush coating.
4. Pre-baking, curing: The coated workpiece is placed on a stainless steel mesh belt, and the workpieces are not allowed to adhere to each other, enter the sintering furnace for 10-30 minutes, and cure for 15 to 30 minutes. The pre-baking, curing temperature and time are mainly determined by the thickness of the coating and the size of the workpiece and the different coating liquid. The conveying speed of the stainless steel mesh belt conveyor is controlled.
5. Post-treatment: If the surface of the fastener is rough after curing, the surface of the fastener can be cleaned with a hard brush.
Post time: Jan-13-2022