This document provides specifications for grinding and polishing mold surfaces for injection molds. It discusses preparation such as tool and material selection, workpiece protection, and inspection requirements. It also covers clamping techniques, polishing procedures like cleaning between steps and determining the process, precautions to avoid going over allowances, and uses of an ultrasonic polishing machine including for removing layers and finishing. Self-inspection and protection of the polished surface is emphasized.

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Specification for grinding and polishing of mold surface
of injection mold
Written By Jasmine HL
First. Preparation before polishing
1. Polishing and polishing personnel must be trained and qualified to obtain an employment
certificate before they can take up their posts.
2. Define the workpiece process requirements, materials and initial conditions, and the
processing position, shape, size and polishing accuracy requirements of this process.
3. Before polishing, it must be checked whether the surface to be polished has defects such as
sags, sags, overcuts, deformation and trachoma, and whether the remaining polishing margin is
sufficient.
4. Reasonably select the applicable tools, fixtures, main and auxiliary materials according to the
process specifications.
5. Appropriate protection of workpieces according to process requirements.
6. Re-confirm steps 1-5 and enter the operation procedure.
Second. The clamping and protection of the workpiece
1. For higher or longer workpieces below 20Kg, a vise clamp is required on the polishing table.
2. For larger and heavier workpieces, front and rear magnets and screw clamps must be used for
fastening on the polishing table.
3. When using a work car to polish and polish workpieces, wedges or related measures must be
used to ensure stable work and safe work.
4. For small, easy-to-scratch and bump-shaped workpieces, rubber plates must be used to
protect the type of surface.
5. Workpieces with sharp corners and corners must be protected with tape or tape to prevent
injury or damage to personnel and workpieces.

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6. For the workpieces that need to maintain the edges and seal position, the side can be fixed
with a stopper (saw blade or iron piece) or a stopper to prevent edge chamfering and rounding.
Third. Content and scope of self-inspection
1. Whether the sealing surface is rounded or rounded;
2.Whether the original mold slope is destroyed;
3. Check the size of each polished surface to see if it exceeds the reserved amount;
4. Whether the fillet at the bottom of the cavity is recessed into the side and bottom;
5. Whether there is an inclination phenomenon;
6. Whether the roughness has reached the requirements of the drawing;
7. After passing the self-inspection, send it to the team leader (or inspector) for inspection.
Four. Precautions for polishing operations
1. Check whether the grinding allowance is sufficient before grinding, and the grinding and
polishing amount cannot exceed the reserved amount:
After grinding, the amount of plane grinding and polishing cannot exceed the reserved amount
by 0.05 ～ 0.06mm;
The amount of grinding and polishing of the unground surface, electric erosion or wire cutting
surface must not exceed the reserved amount of 0.08 ~ 0.1mm;
The unilateral and deep grinding and polishing amount of the ribs cannot exceed the reserved
amount of 0.03 ~ 0.08mm.
2. When working with a polishing machine, you need to pay high attention to prevent grooves
from appearing. If you exceed the allowance, you will not be allowed to process the same part for
a long time.
3. After each sanding, it must be cleaned with whisky, and then the next step of sanding;
4. After each polishing, it must be cleaned with cotton or soft paper, and then polished in the
next step.
5. Before polishing the mold, first determine the processing procedure:
According to different original surface conditions and roughness, select the appropriate sequence
and the appropriate tools for the starting sequence and required sequence (specific diamond file,
abrasive paper, oilstone)
According to the mold cavity geometry, basic roughness and process requirements, determine
the scope of use of power tools and grinding tool heads, and strive to achieve targeted
processing
6. Pay attention to the grinding and polishing of the sealing surface, especially the collision of the
special identification symbol of the part and the sealing surface can not cause rounded corners
and sags;
7. The polishing area requires a clean environment. Pay attention to the protection of the
polished surface during the polishing process;
8. If some parts need to be polished together after assembly, they are not allowed to be polished
separately;
9. After polishing, the polished surface shall be self-inspected and sprayed with anti-rust oil after

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the inspection, and protection shall be done to prevent bumps and scratches;
10. All kinds of oil stone, sandpaper, diamond abrasive paste and diamond file must be placed in
special tool boxes with corresponding labels according to their models and specifications.
Five. Ultrasonic polishing machine
Uses are as follows:
The sintered diamond file is mainly used to remove the electro-processing layer on the bottom
and side planes of the cavity;
Set up electroplated diamond files to remove electro-machined layers and rough cutting marks
on narrow planes, cavity sidewalls, dead corners, and sharp corners;
Clamp various types of oilstones to perform shape and position tolerance repair and increase
roughness caused by rough machining;
Clamp copper, soft and hard wood, and add grinding paste of various sizes to finish polishing the
processed surface.