With the wide application of plastic products, such as cosmetic bottle caps and beverage packaging containers, the surface of plastic mold cavity is often required to achieve the degree of mirror polishing. Polishing can not only increase the beauty of the workpiece, but also improve the corrosion resistance and wear resistance of the material surface. It can also make the mold have other advantages, such as making the plastic products easy to demould and reducing the production injection cycle. Therefore, polishing is a very important process in the production of plastic mold. What are the polishing methods of the daily make-up bottle cap mould?

The following is the commonly used polishing method of daily cosmetic bottle cap mold:

1. Mechanical polishing of the mold of the daily make-up bottle cap

Mechanical polishing is a polishing method to obtain a smooth surface by cutting and plastic deformation of the material surface to remove the convex part after polishing. Generally, oilstone strips, wool wheels, sandpaper, etc. are used. Manual operation is the main method. Auxiliary tools such as turntable can be used for special parts, and ultra precision polishing method can be used for surfaces with high quality requirements. Superfinishing is a kind of special grinding tool. In the polishing liquid containing abrasive, it is pressed on the machined surface of the workpiece to make high-speed rotation motion. The surface roughness of ra0.008 μ M can be achieved by using this technology, which is the highest among various polishing methods. This method is often used in optical lens mould.

2 Chemical Polishing

Chemical polishing is to make the micro protruding part of the material surface dissolve preferentially than the concave part in the chemical medium, so as to obtain a smooth surface. The main advantage of this method is that it does not need complex equipment, can polish the workpiece with complex shape, can polish many workpieces at the same time, and has high efficiency. The key problem of chemical polishing is the preparation of polishing fluid. The surface roughness obtained by chemical polishing is usually 10 μ M.

3 electropolishing

The basic principle of electropolishing is the same as that of chemical polishing, that is, to make the surface smooth by selectively dissolving the tiny protruding part of the material surface. Compared with chemical polishing, it can eliminate the influence of cathode reaction and has better effect. The electrochemical polishing process is divided into two steps:

(1) after macro leveling, the dissolved products diffuse into the electrolyte, and the surface roughness of the material decreases, RA > 1 μ M.

(2) low light level anodized, surface brightness increased, RA < 1 μ M.

Ultrasonic polishing of 4-day cosmetic bottle cap mould

The workpiece is put into the abrasive suspension and placed in the ultrasonic field together. The abrasive is grinded and polished on the workpiece surface by the action of ultrasonic vibration. The macro force of ultrasonic machining is small and will not cause workpiece deformation, but it is difficult to make and install the tooling. Ultrasonic machining can be combined with chemical or electrochemical methods. On the basis of solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution to separate the dissolved products on the surface of the workpiece, and the corrosion or electrolyte near the surface is even; the cavitation effect of ultrasonic in the liquid can also inhibit the corrosion process, which is conducive to the surface lightening.

5 fluid polishing

The purpose of fluid polishing is to wash the surface of workpiece by the high-speed fluid and abrasive particles carried by it. Common methods include abrasive jet machining, liquid jet machining, hydrodynamic grinding, etc. Hydrodynamic grinding is driven by hydraulic pressure, which makes the liquid medium carrying abrasive particles flow through the workpiece surface at high speed. The medium is mainly made of special compound (polymer like substance) with good flowability under low pressure and mixed with abrasive. The abrasive can be silicon carbide powder.

Magnetic grinding and polishing of 6-day cosmetic bottle cap mould

Magnetic abrasive polishing is to use magnetic abrasive to form abrasive brush under the action of magnetic field to grind the workpiece. This method has the advantages of high processing efficiency, good quality, easy control of processing conditions and good working conditions. The surface roughness can reach ra0.1 μ m with suitable abrasive.

The polishing treatment of the daily use cosmetic bottle cap mold not only beautifies the product, but also makes the product not have the ability of injury, which can make the public more at ease.