1、 Excessive polishing: the problem encountered in the daily polishing process is "excessive polishing", which means that the longer the polishing time, the worse the quality of the mold surface. There are two phenomena of excessive polishing: orange peel and pitting. Excessive polishing often occurs in mechanical polishing.

二、工件"橘皮"的措施：当发现表面质量抛得不好时，许多人就会增加抛光的压力和延长抛光的时间，这种作法往往会使表面的质量变得差。可采用以下的方法去补救：

2、 Measures to eliminate the "orange peel" of workpieces: when it is found that the surface quality is not polished well, many people will increase the polishing pressure and prolong the polishing time, which often makes the surface quality worse. The following methods can be used to remedy:

(1)把有缺陷的表面去除，研磨的粒度比先前使用砂号略粗一级，然后进行研磨，抛光的力度要比先前的低一些。

(1) Remove the defective surface, grind the particle size slightly thicker than the previous sand number, and then grind it. The polishing force is lower than the previous one.

(2)以低于回火温度25℃的温度进行应力，在抛光前使用细的砂号进行研磨，以较轻的力度进行抛光。

(2) Stress relief shall be carried out at a temperature 25 ℃ lower than the tempering temperature. Before polishing, grind with a fine sand number and polish with a light force.

三、工件表面"点蚀"形成的原因

3、 Causes of "pitting corrosion" on workpiece surface

由于在钢材中有些非金属的杂质，通常是硬而脆的氧化物，在抛光过程中从钢材表面被拉出，形成微坑或点蚀，产生"点蚀"的主要因素有以下几点：

Some non-metallic impurities in steel, usually hard and brittle oxides, are pulled out from the steel surface during polishing to form micro pits or pitting corrosion. The main factors causing "pitting corrosion" are as follows:

(1)抛光的压力过大，抛光时间过长。

(1) The polishing pressure is too high and the polishing time is too long.

(2)钢材的纯净度不够，硬性杂质的含量高。

(2) The purity of steel is not enough and the content of hard impurities is high.

(3)模具表面生锈。

(3) The mold surface is rusty.

(4)黑皮料未。

(4) The black leather is not removed.

（5）小心地将表面重新研磨，砂粒粒度比先前所使用的粒度略粗一级，采用软质及削锐的油石进行后步骤的研磨才再进行抛光程序。

(5) Carefully regrind the surface. The sand particle size is slightly thicker than that previously used. Use soft and sharp oilstone for subsequent grinding before polishing.

（6）当砂粒尺寸小于1mm应避免采用软的抛光工具。

(6) When the sand size is less than 1mm, soft polishing tools shall be avoided.

（7）尽可能采用短的抛光时间和小的抛光力度。

(7) Use as short polishing time and small polishing force as possible.

工件出现"橘皮"的原因：不规则粗糙的表面被称为"橘皮"，产生"橘皮"有许多的原因，常见的原因是由于模具表面过热或渗碳过度而引起，抛光压力过大及抛光时间过长是产生"橘皮"的主要原因。比如：抛光轮抛光，抛光轮产生的热量会很容易造成"橘皮"。较硬的钢材能承受的抛光压力会大一些，相对较软的钢材容易发生抛光过度，研究证明产生抛光过度的时间会因钢材的硬度不同而有所不同。

Reasons for "orange peel" of workpiece: irregular and rough surface is called "orange peel". There are many reasons for "orange peel". The common reasons are caused by overheating or excessive carburization of mold surface. Excessive polishing pressure and too long polishing time are the main reasons for "orange peel". For example: polishing wheel polishing, the heat generated by the polishing wheel will easily cause "orange peel". The harder steel can bear more polishing pressure, and the softer steel is prone to over polishing. The research shows that the time of over polishing varies with the hardness of the steel.