What are the important details of the acceptance of die casting molds

What are the important details of the acceptance of die casting molds

die-casting production is inseparable from die-casting molds. The quality of the molds directly affects the normal production of the company. As a custom-made die-casting mold manufacturer, we change how to do the acceptance of the mold to maximize the service life of the die-casting mold. The following is a brief description of how to do a good job of mold acceptance.

Inspection and acceptance of the mold after entering the factory

1.1 Evaluation of mold safety

Safe production is the foundation of an enterprise’s survival, and the safety of molds is also one of the important characteristics of molds. Insufficient mold safety will bring great hidden dangers to future production, which can cause serious injuries.

1.1.1 Acceptance of lifting holes

The lifting hole of the mold must meet the relevant provisions of the technical agreement signed by the two parties to ensure the balance of the mold lifting (the lifting balance includes the overall lifting of the mold and the split lifting of the fixed mold); this requires that when making the position of the lifting hole, Give full consideration.

Mould parts larger than 15Kg must have hoisting holes, and the position of mould hoisting holes should be convenient for future mold maintenance, instead of just doing it casually.https://cncmachining.jp

The precision inspection of the mold lifting holes is more important than the quantity and location. The accuracy of the lifting holes must be inspected. These lifting holes should meet the H7 standard, and the depth should not be less than the thread length of the lifting ring of the same specification; the reason is special The accuracy of the lifting hole is emphasized because it is often found in the mold acceptance process that the threaded bottom hole of the lifting hole is too large, and it does not fit well with the thread of the lifting ring. It may even cause the thread slide buckle during the mold lifting process and the mold to fall off. Safety accidents such as personal injury and damage to mold equipment.

1.1.2 Acceptance of mold slider spring

As shown in Figure 1, basically every slider must use a limit spring assembly to ensure the reliable position of the slider after the mold is opened, and to avoid collision between the slider and the inclined guide post caused by the slider’s self-movement. When the mold is closed, the spring is compressed under the drive of the slider. If there is an error in the assembly process, the length L after the spring is fully compressed is greater than the remaining effective length of the screw inside the spring. When the mold is closed, the screw will move from both ends It slips, and the spring bursts out, causing a safety accident that causes personal injury.https://ptjcnc.com


1.1.3 Waterproof acceptance of the travel switch under the mold

In the mold production process, due to the influence of the spraying of the release agent, the stroke switch on the core-pulling cylinder under the mold must be waterproofed to ensure that the switch does not work abnormally due to the influence of the water mist of the release agent. , Resulting in abnormal core pulling and mold collision accidents.

1.1.4 First reset hole thread accuracy inspection

The first reset hole thread must also ensure the thread accuracy. Due to the poor thread accuracy, the first reset rod cannot work normally, which will cause the mold ejector plate to fail to reset correctly, and cause part of the ejector rod to interfere with the slider during mold clamping and cause mold damage.

1.2 Acceptance of the dimensions of the connection between each part of the mold and the outsidehttps://numerical-control.com/

The main connection size between the mold and the outside has four parts:

a) The interface size of the sprue bushing;

b) The size of the oil pipe interface of the core-pulling cylinder;

c) When the mold is first reset, the size of the reset rod hole;

d) The size of the cooling water pipe interface.

Only by passing the inspection of this part of the size can the mold match the company’s production die-casting machine; that is to say, as long as these dimensions are qualified, then the mold can be installed on the company’s die-casting machine for trial mold. Special attention is that some molds are designed to be used on different models of die-casting machines, and the interface size of the die-casting machine may be different. This is to add a washer to the mold sprue sleeve to check the size of the washer It is also essential.

1.3 Appearance acceptance of signs and molds

The mold sign should indicate: part drawing number, mold name, factory date, supplier’s name, mold weight, mold dimensions and other mold-related parameters to facilitate mold management in the future.https://cncmanufacturings.com/

Attention should be paid to the appearance acceptance: the sprue junction should be smoothly connected, the inlay should be smooth and flat, and the surface roughness of the sprue and the mold core should be Ra≤0.8μm. The knife marks left by organic processing and the discharge traces left by electrical processing are absolutely not allowed; the contact area between the ejector plate limit block on the mold foot and the ejector plate should not be too small (as shown in Figure 2), Figure 2 ( a) The circular limit block is used for machining,http://plastic-mold.cn/ but the contact area between the limit block and the mold ejection plate is too small, and the ejection limit is unreliable during the use of the mold, and the top of the die-casting part is unreliable. The traces of the rods vary in depth, resulting in unqualified batches of product parts; after changing to the square limit block shown in Figure 2(b), the mold ejection limit is reliable, and the depth of the ejector rod traces on the product is consistent, and the product quality has been achieved. Guarantee.

Inspection of mold working status

Under normal circumstances, after inspecting and accepting the appearance of the mold, you need to issue a “die-casting mold trial form” to inspect the working status of the die-casting mold. This is the most direct and reliable way of acceptance; the main contents of the trial form that need to be recorded are:

2.1 The movement of the movable part of the mold during the mold trial should be flexible, stable, accurate and reliable, and whether there is skew and jamming.

2.2 The cooling water circuit and hydraulic oil circuit should be unblocked and not leaking;

2.3 The mold is well vented, and whether there is splashing of molten metal;

2.4 Whether all the parts of the mold required to be fixed move relative to each other;

2.5 The movement of the sliding block should be stable. The sliding block and the wedge block should be pressed tightly after the mold is closed, and the contact area should not be less than three-quarters.https://cnc-machining.org/ The limit should be accurate and reliable after the mold is opened;

2.6 The ejector rod of the mold has no abnormal noise, and the ejector returns to the normal position;

2.7 There is no abnormality in the follow-up of the punch, and no abnormality in the ejection of the product;

2.8 There is no phenomenon of cracking, deformation, or product falling out of the fixed mold when the mold is opened;

2.9 Preliminary inspection results of product dimensions after mold preheating;

Quality inspection of product parts

The inspection of product parts should be carried out according to the technical requirements signed by both parties before the mold is opened; the main inspection basis includes: product flat rough drawings, product samples, three-dimensional drawings, special requirements agreed in advance, etc. Of course, the product parts used for inspection should be kicked out of the mold preheating parts, and the product parts produced under the stable conditions of the die-casting process can be used for inspection. The main inspection requirements are:

3.1 Appearance of the product

With well-designed die-casting molds, the number of preheated parts of the mold will be greatly reduced, and the appearance of the produced products is generally very beautiful. The number of defects on the die casting is a simple criterion for testing the forming performance of a mold; according to the relevant technical standards, the appearance of the general product should reach:

There are no defects such as cracks, surface bubbles, mold pulls, looseness, cold separation, flow lines, deformation, shrinkage, under-casting, etc. For the above defects, which can be eliminated through process adjustment, the process can be adjusted. If it cannot be eliminated, it must be corrected The mold is processed, otherwise, the mold can only be judged as unqualified;https://titanium-machining.com/ in particular, it should be noted that a small part of the sample parts produced under the abnormal process, although the sample parts are qualified, does not mean that the mold is qualified. Attention should be paid to mold acceptance. Because abnormal (not within the scope of the process) production process will cause great harm to equipment and molds, and sometimes even safety accidents may occur.

3.2 Full size inspection

A full-scale inspection of the die-casting parts produced by the new mold for the first time can effectively avoid the hidden dangers of product size problems in the subsequent die-casting production, especially the size of the matching parts with other parts; for example, as shown in Figure 3, the hole on the right cover is the same A trademark cover is matched; since this size was not tested during the acceptance of the new mold, the customer only used the trademark cover sample for trial installation during product identification, and the original trademark cover had a relatively large draft angle. , And the external dimensions are controlled at the lower tolerance limit, and the right cover is qualified without any problems in assembly; when the mold produced more than 40,000 pieces, the customer suddenly raised the right cover trademark cover hole size is unqualified; resulting in a large number of product repair processing; after investigation It was found that the customer’s trademark cap mold was replaced with a new mold; the draft angle of the new trademark cap mold was changed, and the size was controlled at the upper tolerance limit; and the hole size of the right cover mold was just smaller than the lower tolerance limit.https://beryllium-copper.com/ The fluctuation of dimensional tolerances caused later assembly difficulties. If a full-scale inspection of the die-casting parts produced by each new die-casting mold is carried out at the beginning to ensure that each dimension is within the tolerance range, similar problems can be effectively avoided.

3.3 Die casting performance inspection

With the continuous expansion of the scope of application of die castings, the requirements for various properties of die castings are also increasing. Commonly used are destructive tests, air tightness tests, and pores (shrinkage) inspections after machining. It is necessary to conduct related performance tests on the first part of the die casting; when the die casting cannot meet these performance requirements, it is necessary to conduct a targeted analysis of the mold, find the cause, and solve it; sometimes some of the mold gate is very subtle Changes in the mold will change the filling state of the mold, and the filling state of the mold will have an impact on the structure, compactness, and mold exhaust of the product; resulting in a change in the quality of the produced die casting.

Mold stability and acceptance of spare parts

4.1 Acceptance of mold stability

Due to the poor working conditions of the die-casting mold and high requirements on the stability of the mold, some hidden defects in the design and manufacture of the mold are not enough to be exposed without a continuous production process. Therefore, the die-casting mold must be subjected to a mold quality For stability inspection, the production batch is generally set as: 1500 molds for aluminum and magnesium alloys, and 3000 molds for zinc alloys.

The quality and stability issues must be effectively resolved to confirm the final qualification of the die-casting mold; https://china-turning.com/the stability issues are prone to:

a) The mold core is broken;

b) The slider is soaked in water and stuck;

c) Running water on the parting surface;

d) The ejection deformation caused by insufficient mold strength;

e) The die-casting part is cracked or strained when the mold is opened;

f) The die-casting part falls out of the fixed mold when the mold is opened;

g) Local sticking of the mold (mostly at the flushing part of the gate);

h) The product size is unstable and the geometric tolerance exceeds the standard;

4.2 Acceptance of mold accessories

On the premise of ensuring that the die-casting parts are qualified, the mold parts attached to the mold factory and the cores installed on the mold are checked and accepted in detail according to the mold parts drawings to ensure that the drawings are consistent. This is crucial for future mold maintenance and parts production. Important; for duplicating molds, at the beginning of the production of molds, the mold factory is required to design and manufacture molds according to the original mold accessories, and do the company’s standardization of the mold spare parts as much as possible to ensure the original mold accessories It can also be used; in this way, the inventory and waste of mold parts can be greatly reduced.https://cncoperating.com/ For serialized product parts, when making molds, the mold factory can also be required to design and manufacture the standard preparation parts; the standardization of mold parts is very conducive to the reduction of die-casting mold maintenance costs.


Concluding remarks

The acceptance of die-casting molds is a process of comprehensive examination of die-casting molds. It should be strictly checked and treated seriously; from this, hidden dangers that may exist in the use of molds in the future are found to facilitate subsequent safe production; some mold unstable factors are found during mold trial. Taking reasonable response measures is conducive to the stability of die casting quality in the future.