What is the standard development process for injection molds

I. Drawing mold diagram

Before drawing the general assembly diagram of the mold, the process diagram should be drawn, and it should meet the requirements of the part drawing and process information. The dimensions guaranteed by the next process should be marked on the drawing with the word "process dimensions". If there is no mechanical processing after molding except for burr repair, the process diagram is identical to the part drawing.

The part number, name, material, material shrinkage rate, and drawing ratio should be indicated below the process drawing. Usually, the process drawing is drawn on the general assembly drawing of the mold.

Try to use the scale of 1:1 to draw the general assembly drawing, start from the cavity first, and draw the main view and other views at the same time.

The general assembly drawing of the mold should include the following contents.

Structure of molding part of the mold

The structure form of pouring system and exhaust system.

The parting surface and the way of taking parts from the mold.

The shape structure and the position of all connecting parts, positioning and guiding parts.

Marking cavity height dimensions (not mandatory, as needed) and overall dimensions of the mold.

Auxiliary tools (picking and unloading tools, calibration tools, etc.).

Serialize all parts in order and fill in the detailed list.

Mark the technical requirements and instructions for use.

Technical requirements of the general assembly drawing of the mold.

Performance requirements for certain systems of the mold. For example, the assembly requirements of ejector system and core pulling structure of slider.

Requirements for mold assembly process. For example, the fitting gap of the fitting surface of the parting surface after mold assembly should be no more than 0.05mm The parallelism requirement of the upper and lower part of the mold, and point out the size decided by the assembly and the requirement of the size.

Mold use, assembly and disassembly method.

Anti-oxidation treatment, mold numbering, lettering, marking, oil seal, storage and other requirements.

Requirements concerning mold testing and inspection.

The order of drawing parts from the general assembly of the mold should be as follows: first inside, then outside, first complex, then simple, first molding parts, then structural parts.

The requirements are as follows.

Graphic requirements

Must be drawn to scale, allowing enlargement or reduction. The view selection is reasonable, the projection is correct, and the arrangement is appropriate. In order to make the processing patent number easy to read and easy to assemble, the graphics should be consistent with the general assembly drawing as far as possible, and the graphics should be clear.

Marking dimensions require uniformity, concentration, order and completeness

The order of marking dimensions is: first mark the main parts size and out of the mold slope, and then mark with the size, and then mark all dimensions. In the non-main parts of the diagram first marked with the size, and then marked all the dimensions.

Surface roughness

The most applied one roughness marked in the upper right corner of the drawing, such as marked "the rest of 3.2." Other roughness symbols are marked on each surface of the part.

Other content

For example, the part name, mold drawing number, material grade, heat treatment and hardness requirements, surface treatment, graphic scale, free size of the processing accuracy, technical instructions, etc. should be filled out correctly.
 

II, Proofreading, review drawings

The relationship between the mold and its parts and the drawing of plastic parts

Whether the material, hardness, dimensional accuracy and structure of the mold and mold parts meet the requirements of the plastic parts drawings.

Plastic parts

Whether the flow of plastic material flow, shrinkage, fusion marks, cracks, mold slope, etc. affect the performance, dimensional accuracy, surface quality and other requirements of plastic parts. Is there any shortage of pattern design, is the processing simple, and is the shrinkage rate of the molding material selected correctly.

Molding equipment

Is the injection volume, injection pressure, clamping force sufficient, the installation of the mold, the southern core of the plastic parts, and the demolding problem, and whether the nozzle of the injection machine is in proper contact with the querulous sleeve.

Mold structure

Does the position of parting surface and finishing accuracy meet the needs, does overflow occur, and can the plastic parts stay on the side of the mold with ejector device after opening the mold.

Whether the mode of mold release is correct, whether the size, position and number of promotion rod and push tube are suitable, whether the push plate will be stuck by the core, and whether it will cause abrasion to the molded parts.

Mold temperature adjustment aspect. The power and quantity of the heater; whether the location, size and quantity of the flow line of the cooling medium are suitable.

The method of dealing with the side concave of the plastic part making, whether the mechanism of removing the side concave is appropriate, for example, whether the slider and push rod in the inclined column core extraction mechanism interfere with each other.

The location of the pouring and exhaust system, whether the size is appropriate.

Design drawings

Assembly drawings on each mold parts placement part is appropriate, whether the representation is clear, there is no omission.

The part number and name on the part drawing, the production quantity, the part made or purchased, the standard parts or non-standard parts, the precision of the parts with processing, the correction processing and allowance at the high-precision size of the molded plastic parts, the material of the mold parts, heat treatment, surface treatment, the degree of surface finishing are marked and described clearly.

Parts of the main parts, molding parts working dimensions and fit dimensions. Dimensional figures should be correct, do not make the producer convert.

Check the view position of all parts and assembly diagrams, the projection is correct, whether the drawing method is in line with the national standards of cartography, there is no omission of dimensions.

Calibrate the processing performance

Whether the geometric structure, view drawing and dimensional scale of all parts are conducive to processing

Recalculate the main working dimensions of auxiliary tools

Professional proofreading in principle according to the designer's self proofreading project; but focus on the structural principle, process performance and operational safety aspects. When the graph is digested, the graph is depicted according to the national standard, and all dimensions and technical requirements are filled in. After the drawing, self-calibrate and sign.

It is the customary practice to have the relevant technical personnel of the tool manufacturing unit review, countersign and check the manufacturing process before sending it to the sun.

Preparation of manufacturing process card

By the tool manufacturing unit technical personnel to prepare the manufacturing process card, and ready for processing and manufacturing.

During the manufacturing process of the mold parts, the inspection should be strengthened and the focus of the inspection should be on the dimensional accuracy. After the mold is assembled, the inspector will carry out inspection according to the mold inspection table, the main thing is to check whether the performance of the mold parts is good or not, only in this way can the manufacturing quality of the mold be guaranteed.
 

III, Mould test and mold repair

Although it is in the selection of molding materials, molding equipment, mold design under the expected process conditions, but people's understanding is often imperfect, so must be completed in the mold processing, mold trial test, to see how the quality of molded parts. After finding always, carry out the mold repair to exclude the error nature.

There are many kinds of defective plastic parts, and the reasons are very complicated, there are reasons for the mold, there are also reasons for the process conditions, the two are often crossed together.

Before repairing the mold, we should analyze and study the defect in detail according to the actual situation of the molded part, and find out the cause of the defect and propose remedial methods. Because the molding conditions are easy to change, so the general practice is to change the molding conditions first, when changing the molding conditions can not solve the problem, then consider repairing the mold.

Repair the mold should be more cautious, not very sure not to take rash action. The reason is that once the mold conditions are changed, it is not possible to make a major transformation and restore the original state.

The performance of the parts is good, only then can slang language mold manufacturing quality.
 

Ⅳ, organize information for archiving

After the test, if the mold is not used for a while, it should be completely wiped off the mold dross, dust, oil, etc., coated with butter or other anti-rust oil or anti-rust agent, off to the storage place for safekeeping.

From the beginning of the design of the mold to the successful processing of the mold, inspection and passing, the technical data generated during this period, such as the mission statement, parts drawings, technical specifications, mold assembly drawings, mold parts drawings, base drawings, mold design instructions, inspection record sheets, test mold repair records, etc., according to the provisions of the system to organize, binding, numbering for archiving. This seems to be very troublesome, but it is useful for repairing molds and designing new molds in the future.