天美影院

When designing molds, sometimes certain areas of the product are very high or very low. We might hollow out a section and fill it with other materials. Using a single material for high areas can save on mold core thickness, while low or inaccessible areas can be conveniently processed using inserts.

What are Inserts?

Inserts are a type of mold component. They refer to mold components embedded in the mold core.

Inserts can be square, round, flat, and, like all mold components, require high precision. Generally, they are custom-made according to the mold’s needs.

Properties of Inserts

Types of Inserts: Insert pins, insert blocks, insert pillars, insert rings, etc.

Materials: SKD61, SKH51, ASP23, SKD11, etc., or the same as the corresponding mold core material.

Hardness: Above 50 HRC.

Standard Precision: ±0.01mm, depending on the specific mold precision requirements.

When are Inserts Needed?

1. Saving Mold Materials

As we know, mold materials are typically ordered in regular-shaped blocks. The materials for the core and cavity are determined by the highest point.

Therefore, whether it’s the core or cavity, if a certain area is higher than other places, it can be reduced by making an insert, thus lowering the height of the mold core and saving mold material.

2. Easy Mold Modification

For areas of the mold that are frequently modified, inserts can be made and replaced as needed. Spare inserts can also be prepared for future modifications, making it easier to update the mold.

For example, some ODM manufacturers can change the product’s brand by just modifying the logo. In this case, we can make the logo area on the mold into an insert, eliminating the need to create a new mold.

3. Improving Mold Venting

Mold venting is crucial to prevent trapped air in the mold cavity, especially in deeper rib areas, which can cause defects such as bubbles, sink marks, or burn marks in the product.

We can add inserts to areas requiring venting, using the gaps between inserts for air release.

4. Simplifying Mold Processing

In deep rib areas of injection molds where machining tools struggle to reach, people often use EDM (Electrical Discharge Machining).

However, EDM is slow and inefficient, so, we use inserts to simplify the process and aid venting.

Deep rib areas also require tedious hand polishing for mold release. By making these areas into inserts, they can be removed and polished separately, simplifying the process.

5. Extending Mold Life

Areas of the mold prone to damage, such as thin or sharp regions, can be made into inserts. We can place the Damaged inserts, extending the overall mold life.

6. Conducting Mold Temperature

Generally, molds are cooled by water channels, but some areas cannot accommodate these channels. Inserts made from materials with good thermal conductivity, like beryllium copper, can help dissipate heat in these areas.

Drawbacks of Using Inserts in Molds

However, there are certain drawbacks to using inserts, such as:

1. Increases the difficulty of mold assembly;
2. Causes flash (excess material) around the inserts;
3. Sometimes raises mold design and machining costs, thereby increasing overall costs;
4. Too many insert structures can affect the design of the mold cooling channels;
5. Too many insert structures can affect the strength of the mold core.

Processing of Inserts

To improve processing efficiency, some large molds are divided into several smaller parts for separate processing, which can save time.

In general, there are two types of inserts: through inserts and blind inserts.

For some smaller inserts, Y-CUT wire cutting can be used, with head for positioning.

For larger inserts, such as those above 60×60, blind inserts can be used and secured with screws. Although processing is relatively difficult, this ensures the strength of the mold.

Insert Materials

For inserts without shut-offs, the material can be the same as the mold core material.

For the insert with shut-offs, the material can be the same as the mold core but with a higher hardness by 2 degrees, or different materials with different hardness.

When designing the heads, consider the ease of processing and DATUM to facilitate wire cutting and grinding machine processing. The head is generally designed as 5×2.0mm or 4×3 mm.

The head should be placed in a straight position on the insert, as shown:

The head should be 0.5-2.0mm shorter than the straight edge to facilitate wire cutting of the radius.

For irregularly shaped inserts that are unsuitable for insert head, a 1-2 degree taper can be applied around the perimeter to fit the insert in place, known as a tapered insert.

When round inserts have directionality, anti-rotation measures are needed. The simplest method is to mill a platform on the insert head, using the flat position to prevent rotation.

Insert Structure: When the product has a shoulder, deep ribs (over 10mm), or is transparent, inserts can be used for easy processing, polishing, and structural modification. The mold core should have at least 25mm to the edge and often uses well water cooling.

Tolerance requirements for inserts are below 0.05, corresponding to the sealing bottom inserts.

Some inserts are designed for venting, with many layers of venting inserts fastened with ejector pins, or made of breathable steel.

Summary

Inserts are a common structure in molds, with clear advantages despite some drawbacks.

When designing molds, determine which areas require inserts based on the product structure and avoid unnecessary inserts.

Note that insert marks or lines are usually present on molds, and client confirmation is needed during mold review to ensure parts acceptance.