How to test the mold?

Preliminary preparation for model test T1

Understanding Injection Molding Products

Engineers need to know the shape and structure of the product in advance, the possible structure problems and the characteristics of the product, so that they can quickly find out, adjust and solve the problems in time when testing the mold.

drawings

Prior to T1,  drawings shall be prepared. If no drawings are provided by the customer, the manufacturer shall note the length and width according to the product mold design, which is convenient  to measure. At least 2 or more dimensions shall be available for timely adjustment during the test.

measuring tools

According to the drawing, prepare suitable measuring or inspection tools, and adapt samples to facilitate measurement, inspection and verification.

material properties and processing conditions

Engineering needs to be familiar with the physical property sheet of the raw material and ,be able to judge whether the test conditions are within a reasonable range.

According to the product weight, mold characteristics, a mold test sheet will be issued to facilitate the production of suitable machines.

The mold test sheet shall be marked with waterway connection.

And the mold test shall be conducted according to Mold Flow conditions.

Equipment

It is also necessary to confirm the testing auxiliary equipment ,such as the number of water pipes, the number of Water pipe joint ,temperature controller and to prepare thermometers, etc.

Relevant participants

Quality personnel shall be notified to participate in the mold test

DFM 

The engineer in charge needs to prepare DFM to check the mold structure in detail and find out the problems. Any errors need to be recorded in the mold test  table for feedback and correction.

Check the waterway connection and set various conditions.

Responsible engineers need to check the waterway connection  (following DFM ), mold temperature , barrel temperature  and injection conditions .

Any non-conformance items need to be corrected immediately. If cannot be corrected immediately, they need to be recorded in the mold test table so as to solve the problems later.

90-95% shot

Before the product is ejected, the first shot volume needs to be estimated,stabilize the slow-shooting product 90-95%, and keep the barrel storage material about 10%, and then slowly add 10 Pascals until the appearance of the product is optimal.

When the mold has a multi-cavity, it is necessary to see whether the feeding of each cavity is uniform, otherwise it is necessary to keep samples to facilitate the adjustment of the mold.

Sample size and appearance

After the appearance of the product is adjusted to an acceptable state, take the 2-shots product, soak in water for 2-5 minutes, measure the size, take the product size as the standard, and adjust the size to the design limit .

Secondly, the structural appearance shall be adjusted and the injection parameters shall be fine-adjusted, so as to get the required sample quantity under the best conditions (no shrinkage, burrs, short shot, melting lines and other defects) of the external structure, and record the conditions for the next use. If the defects cannot be corrected, sample records shall be kept for the reviewing and improving the countermeasures.

mold fitting

If the product has flash after being molded, the fitting worker should be called immediately to remove the flash, and the maximum mold locking pressure should be set at low speed and low pressure of about 30 BAR to confirm the mold matching tightness.

DOE analysis

If the satisfactory size or deformation degree of the product cannot be reached under the multiple adjustments, the engineering and test technician should discuss, and the engineering lists the DOE analysis form, makes adjustment and combination for the parameters that can be affected by the product problem points, tests one by one according to the plan, and makes condition records and sample records for each changed condition, CPK analysis, and after testing and evaluation, selects the best condition for next reference.

• Wear safety helmet and prepare the wrench, rust inhibitor, rag, etc. to disassemble the mold tool.


• Check the crane:

Should check the crane movement status and the function of each button, especially the emergency stop button, if there is any problem, stop immediately, and hang the "prohibited use" sign to notify the repair.

•  Check the wire rope and shackle:

Check if the wire rope used is in the loop, the strand is broken, and the mold is too heavy? If necessary, replace the wire rope immediately;;

Shackles used for lifting shall not have bending deformation and shall not be inconsistent with the tonnage of the lifting mold.

• Inspect the mold:

According to the size of the mold, choose the machine that can be installed.

Whether the mold uses the unscrewing mechanism, if yes, please prepare the oil pipe and the oil pipe joint, and check them, if it is found that the screw thread is broken, please do not use it, so as not to damage the good screw thread, and there will be oil leakage.

Whether the cooling water pipe joint of the mold is installed in good condition, and whether the waterway is unobstructed (check through the air gun);

Install the lifting ring (curved lifting ring is forbidden to be used). The depth of screwing the lifting ring into the mold must be greater than 1.5 times of the diameter of the lifting ring.

If the surface of the lifting ring and the mold have not been fit well and gaskets must be used to prevent bending and fracture of the lifting ring.

material preparation

1. Confirm the material number/type according to the drawing.
2. Confirm the color master number and mixing ratio (if color master required)
3. Check the material in the hopper, and there is a sign on the hopper indicating the materials 
4. Confirm the proportion of recycled materials, drying temperature and drying time (according to the material properties and product requirements)

mold preparation

1. Confirm the mold number
2. Check whether the mold has special requirements such as insert and core pulling
3. mold inspection: check  the mold appearance such as positioning ring and hot runner interface.
4. Inspection of mold fittings: check the water pipe joint and length , clamping plate, bolt length of clamping plate, suspension block, etc.
5.  the mold nozzle R match with the machine nozzle

Machine preparation

1. Confirm whether the mold can be installed on the injection molding machine: the maximum clamping force of the machine, the size of the mold, the thickness of the mold, the core pulling, and the blowing device.
2. Check whether the ejector bar of the machine suitable for the mold
3. Check whether the screw has been cleaned
4. Check whether the mold temperature controller, robot, automatic mixer and automatic suction machine can work normally: the robot is matched with the mold
5. Confirm and check product drawings/samples (if any) and important dimensions
6. Prepare relevant tools



1. Before bolting the mold, the machine should be cleaned. Check the appearance of the mold such as positioning ring, ejector pin hole, core pulling and unscrewing mechanism and hot runner system interface. 

2. Install the eyebolt (curved lifting ring forbidden). The depth of screwing the eyebolt into the mold must be greater than 1.5 times of the diameter of the eyebolt . If  the eyebolt and the mold have not yet been fit well and gaskets must be used to prevent bending and fracture. 

3. Place the mold between the movable and fixed plates and maintain a certain height. Connect the water pipes and related interfaces (if any) under the mold. 

4. Align the location hole and adjust to align the mold into the location hole of the machine. After determining the horizontal balance, first slightly bolted a clamping plate on mold.

5. Close the operation door, close the mold, start the automatic mold adjustment 

6, clamping force adjustment 

7. After completion, open the operation door and fasten the movable fixed mold  plate. 

8, loosen the rope, remove the security bar

9. Connect the water pipes and related equipment (if any) on both sides of the mold. 

10. Connect the hot runner plug, preheat the mold 

11. Close the operating door and set the mold to a lower temperature (it cannot be directly set to the final molding temperature).

12, ejector pin retract

13. Open the mold and check the parting surface.

14. Adjust the ejection force, speed and ejection times of the ejector pin.

15, mold opening and closing adjustment (mold opening and closing speed, position, low-pressure protection position, monitoring time), find out the correct speed-fast -> slow -> slow again when closing the mold, slow -> fast -> slow down when opening the mold. The position switch of mold closing selects the contact between guide pins and guide sleeve. The smaller the low pressure protection pressure is, the better it will protect the plastic mold. The monitoring time could be 0.1s larger than the actual mold closing time.

16. Check the operation  by shooting into air and adjust it to be stable and appropriate.

17. input the process parameter data (please adjust within a small range, generally 5%). It is not necessary to follow exactly the same value of the sheet. Please refer to the relevant material temperature  table for the temperature setting range of materials with various properties)

18. Loading: Before loading, it is necessary to verify  the raw materials.

19. Retract the barrel and shot to prevent sticking to the mold.

20,For hot runner molds, shooting-to-air shall be done before this to ensure smooth melt flow . 1) cardboard shall be used between the movable and fixed molds to catch the injected materials; 2) Adjust the temperature appropriately before shooting(and return it to normal value after confirming.)

22, semi-automatic production, check the injection molding condition, adjust the injection pressure and injection speed. 1) For smaller parts, screen should be used to cover both sides of the mold to prevent parts from splashing; 2) set the maximum injection pressure according to the actual injection pressure;

23. Find the pressure maintaining switching point, shot the product to 95%~98%, and then apply hold pressure .

24. Adjust the back pressure, screw speed, and the metering time is 65%~75% of the cooling time, and the best is 75%.

25, turn on the monitoring, set the counter

26. Weigh the product at the switching point and record the weight comparison with the switching point on the card. If for PPAP, 2 shots of products shall be collected, 1 shot shall be put into the sample package, and the other shot, engineer shall keep for future reference.

27,Compare the product with the sample, if the mold insert cores are changed, the product number must be noted.

28, send to QA for inspection, send 5 shots of products to QA for inspection, and provide a total of 300 shots for future work

29. After the production is finished, the machine can not be stopped until the last shot is collected and keep for future work

30. For PPAP, the technician shall note the process parameters and fill in the cards, and send for next operation.

32. In case of alarm or shutdown during production, the safety door need to be open,it need retract the barrel to prevent the spray.

33. When starting the machine again, shoot the material to the air to prevent mold sticking.

downtime maintenance.

35. Close the mold and retract the barrel. Turn off the mold temperature controller and hot runner

36. Turn off the electric heating after cleaning the screw.

37. releasing the ejector pin, the ejector pin must be released when closing the mold, otherwise it may cause the slider to crash the ejector pin.

38. Open the operating door, bolster the lifting block, and hang the mold tightly. The rope should not be too tight, but can be slightly shaken.

39, un-bloster the clamping plate, remove the mold from the machine

40. Lift the mold and place the right place.

41. Clean up the injection molding machine and hand over the runner and failed products.