Mold designers need to pay attention to some details of mold structure and part design. Details determine success or failure. Of course attention to detail requires level and experience. Don’t worry, this article contains 12 general details. Get these details to help your design.

The parts have sharp corners or sharp edges, and the parts are easy to collapse when nitriding. The absence of an R angle creates processing stress. Parts will fail prematurely. If the core or cavity is not set chamfer. This can cause resistance during injection molding.

The chamfers of the template are uniform and look beautiful. Depending on the size of the template, use different chamfers.

Assembly holes for parts and heads for shaft-type parts. A suitable chamfer is required. This facilitates assembly and is less prone to damage. And it is easy to knock the dowel pin into the assembly part. As the picture shows

A.The edges of the hole and the wear block are broken.

B.There must be a certain distance between the holes. The margin should be at least 3-6mm.

C.Avoid placing the cooling water holes too close to the tapped holes. Eyelet holes to avoid interference with water pipe joint holes.

D.There is a gap between the cooling water hole and the cooling water hole.

E.The hole should not be too close to the outside of the part.

F.There should be a gap between the cooling water hole and the ejector hole.

The diameter of the via of the hexagon socket screw cannot be too large. Otherwise, the contact area of the screw plane will be reduced.

If the bevel has threaded holes, be sure to make a plane on the bevel. as the picture shows. If you drill directly on the inclined surface. The drill and tap will easily break and damage the workpiece.

Cooling water holes that intersect in the same plane. One hole must be more than half the diameter of the bottom of the other hole. In particular, avoid the intersection of the bottom ends of the two holes. Otherwise, the drill is easily broken when punching, as shown in Figure (a). Figure (b) is correct.

The 3D shape of the head of the cooling water hole must not be flat. It is wrong as shown in Figure (a). It should be designed with a sharp angle of 120 °. As shown in Figure (b).

1)Arrange the screws near the part where the joint is most stressed.

2)The countersunk holes of the hexagon socket screws are required to be uniform and meet the standards.

3)The mechanism for preventing the nut of the rotating mechanism from loosening should be reliable.

4)The effective depth of the tapped hole must exceed the length that the screw needs to be screwed in. Generally the effective length of the screw is 1.5-2 times the diameter of the screw.

5)The eyebolts must not interfere with other parts. Allow sufficient space for the nuts to be tightened. Ensure space for bolt installation and removal.

1.Eyebolt screw holes should be chamfered. as the picture shows. The screws are not close to the template, and there is a gap on the plane. The screws are bent during lifting, which poses a hidden danger.

2.Set the position of the eyebolt reasonably. Pay attention to the center of gravity of the mold after lifting.

3.When mounting the die, the die upward only 5 °. Otherwise, the mold installation is difficult.

4.Consider the allowable load of eye bolts.

1.Parts assembled with each other must have two dowel pins of appropriate size. Cannot be replaced with screws.

2.The distance between the two dowel pins should not be too close. The positioning pins and hex screws should be staggered, so as to obtain higher positioning accuracy.

3.Dowel pins should be easy to remove. Therefore, the pinholes must be through and properly sized.

4.For asymmetric structure. Dowel pins should not be arranged on symmetrical parts. Prone to errors during assembly.

5.When lateral force is applied, do not rely only on pins and screws to fix the wedge.

6.Remove unnecessary dowel pins.

1. Try to use standard parts when designing the mold.

2. Do not misuse the standard of standard parts.

3. The selection of standard parts for mold structural parts must match.

One pair of molds must be equipped with two lock blocks. Prevent mold opening during transportation and handling. Cause mold damage and safety accidents. As show the picture.

The function of the mold opening slot is to facilitate the opening of the mold. The four corners of the A plate and the B plate have grooves. Standardize the size, depth, and dimensions of the die slot. As show the picture.

1)Threaded eyelbolt holes should be provided on each side of the mold.

2)The mold should be equipped with support columns. Used to protect the core pulling mechanism and the oil cylinder. Support pillars for large molds require stepped insert form work. As the picture shows.

1.Try to avoid the size of the mold to be decimal. It is wrong as shown.

2.Avoid designing parts into asymmetric shapes.

1)The reference angle of the mold base is the right-angled edge of the offset guide hole.

2)When ordering a standard mold base, first design a 2D drawing. As the picture shows.

3) The template material should match.

4) Set the mold opening slot.

5) Pay attention to the interference of the eyebolt holes.

1) Mark surface roughness according to quality requirements.

2) Surface roughness can be divided into: mirror smooth surface, molding surface, mating surface, non-mating surface.

3) The surface roughness marking should be compatible with the part processing method.

4) The surface roughness requirements of the core and cavity of the transparent plastic mold are consistent.

5) The surface roughness of the mold cavity of electroplated parts must be consistent.

The details about injection molds go far beyond these 12 points. Regardless of mold design and manufacturing, accumulation of experience is required. Details determine success or failure. If you have any questions about injection molds, please contact us. We are professional.

We may need metal casting molds in many field. Do you know the process of manufacturing metal casting molds?

To form the sprue — a passage through which you’ll pour the metal — measure the depth of the cope, and mark this distance with tape on the side of a section of thin-walled 3/4-inch pipe. Push the pipe straight down into the sand in the cope, in a spot where it will not hit the pattern. Twist the pipe back and forth to cut an opening through the sand, stopping when the tape mark meets the surface of the sand. Use a slick to carve a funnel shape in the sand around the pipe, beveling the edges of the sprue opening. Then slip the pipe out, with the sand core inside, leaving a passageway through which you’ll pour the molten metal.

On the other side of the pattern, form the riser opening — the passage into which excess metal will rise — by using a slightly larger diameter pipe to cut through the sand in the cope.

Use a 1/16-inch welding rod or a stiff wire (a bicycle spoke is ideal) to poke channels through the sand in the cope, so that hot gases can escape. Push the rod into the sand, stopping about 1/2 inch from the pattern. Make about a dozen vents over the pattern area.

Lift the cope from the drag and set it on edge, off to one side, where it will not be disturbed.

Before lifting the pattern from the drag, firm the pattern edge of a water-based sand mold by moistening it with a molder’s bulb or a small brush dipped in water. This will help to keep the sand from collapsing when the pattern is removed. Screw draw pins into the holes in the back of the pattern and lightly tap the pattern to loosen it from the sand. Then gently pull on the draw pins, lifting the pattern straight up and out of the casting cavity.

Using a piece of sheet metal bent into a 1/2-inch-wide U shape, cut a channel, or gate, running from the casting cavity to the riser position. Lift out a bit of sand at a time, forming a gate slightly smaller than the diameter of the riser and slightly shallower than the depth of the casting cavity. Scoop out a similar gate from the casting cavity to the sprue position. For large molds, cut several gates to the sprue and the riser from various parts of the casting cavity. Blow out or tamp down any loose bits of sand in the gates.

Rebuild crumbled sections of the casting cavity by adding bits of moist sand, smoothing it into place with molding tools. Tamp down or blow away all loose sand to prevent it from mixing with the molten metal when the metal is poured.

Replace the cope over the drag and set the flask, still on the bottom board, in the sandbox near the furnace. If you are not going to pour the casting immediately, cover the mold to keep dirt from falling into the sprue and riser.

With a helper, lift the crucible shank and hook its safety lock over the lip of the crucible by pushing the latch forward. Lift and tilt the crucible a few inches above the mold, pouring the molten metal quickly and steadily into the sprue, or molten metal passage, into the cast. Stop pouring when the metal nearly reaches the top of the riser. Immediately, while it is still molten, pour all the extra metal into the ingot mold. Leave the casting mold in place until the metal in the sprue and in the riser is hard. To test the newly cast metal for hardness, tap it with the tongs.

When the metal has hardened, carry the mold to the sand-storage area. Wearing gloves, separate the cope and the drag. Lift out the hot metal casting with tongs. Break apart the sand in the mold, and dump it back into the sand-storage container. Set the casting aside to cool, leaving in place the extrusions that the sprue, riser, and gates formed.

When the casting is completely cool, cut off the gates with a hacksaw and file down the rough areas. Finish the surface as desired.

After the plastic part is injection molded, the plastic part is taken out from the mold cavity.Whether using a single or multiple ejector mechanism, ejection is done in one go.However, sometimes it is difficult to fall off at one time due to the special shape of the plastic part.Can not meet the needs of production automation.

However, adding another action affects the production efficiency of the plastic parts.So ejection system is an important part.The main reason for the difficulty of ejection is that the gate or plastic part is tightened in the mold.The reasons for this are:

(1) The ejection structure is unreasonable or improperly positioned.

(2) The draft is not enough.

(3) Low mold temperature or poor ventilation.

(4) The surface of the sprue wall or cavity is rough.

(5) The nozzle diameter is larger than the feed port diameter or the two do not match.

(1) The barrel temperature is too high or the injection volume is too much.

(2) The injection pressure is too high or remains cool and pressure for a long time.

The traditional method of ejection system plastic parts is roughly divided into four types: ejection, push, pump and spin.

Now there is a new release stripping technology can solve the problem of plastic parts.Nano release coatings are applied to the surface of the plastic mold and to the surface of the mold insert.The coefficient of friction of these surfaces can be significantly reduced.High gloss finishes can be achieved without the use of conventional release agents. Nano materials reduce the maintenance of machines or tools and extend the time of uninterrupted production.Plastic mold production plays the biggest role and reduces waste.Nano release coatings have greatly increased the productivity of the plastic mold manufacturing industry.

In recent years, with the advancement of polymer technology, advanced manufacturing technology, computer-aided technology (CAD, CAM, and CAE) and other related technologies.Large-scale injection molds account for an increasing proportion of the entire mold output.Such as car bumpers, dashboards, TV housings, washing machine inner cylinders, TVs, air conditioning machine parts, tubs, barrels, turnover boxes and other large injection mold products.

Due to the high cost of large injection molds. Therefore, the requirement of design and manufacture must be a success. Avoid rework. It is not allowed to be scrapped due to improper design.

In terms of design, manufacturing, and injection molding technology, large molds are basically the same as ordinary injection molds.But large models have many unique features. Such as strength design, pouring system design, structural design, processing methods.In the design process, if there are mistakes in these aspects. It can cause huge losses.

Large molds have large pressure, large cavity size, large deformation, and large core support distance.Structure must be designed to strengthen the knot solve these problems.For example, in the cavity, the edge of the core design stop cone positioning. The support column is designed on the bottom surface of the core.

Designing small molds for cavity insert and core insert.Often designed as a whole. This structure is simple and easy to process.For large molds, monolithic structures are generally not used. Instead, a modular cavity structure is used.The purpose is to save precious metals and reduce the amount of machining. Easy to grind, polish, and heat treat.

In general, the larger the mold, the more complex the molded parts.If a modular structure is adopted, its superiority will be greater.However, attention should be paid to the fact that, when using a modular structure, in addition to satisfying its rigid conditions, the form of its combination must also be carefully considered.

Nowadays, various mature injection molding processes bring more creative space to designers and engineers. They can inspire their inspiration to enhance the appearance and ergonomics of the product.

Often a single material or color does not meet the manufacturing requirements of the product. The materials for these products range from plastics to metals.

In the past, this was done by using additional secondary services or more complex assemblies to create finished products. However, today’s multi-material injection molding largely eliminates these additional requirements, making it easier to manufacture complex finished products, faster, and cheaper.

It is a single component made from a combination of two or more plastic or elastomeric materials. You can read the definition in Wikipedia. Before that, I thought this was a category of overmolding.

I think overmolding is a big category. Only some parts are similar to multi-material injection molding or insert molding, so the overmolded part is classified into multi-material injection molding.

In fact, I also found different voices, but I prefer authority. Then I divide the multi-material injection molding into:

1.Multi-component injection molding

2.Multi-shot injection molding (MSM)

3.Over-molding

Also referred to as sequential injection molding, multi-shot injection molding refers to creation of multiple layers relative to the starting axis of the initial mold. In other words, the warm, heated materials are inserted into the mold in a very specific sequence one after another.

This creates a layering effect between materials while maintaining relatively high-energy interactions at material boundaries. This is important because it implies that the inter-layer bonds are stronger in many cases than when the layers are applied to a previously cooled part, as is more closely the case of over molding. While there are other applications, this operation is preferred when varying molds (different geometries) are desired between material layers.

This technology or process is nothing new, and is simply used for the production of two-color plastic parts or products. The two materials form a single plastic part by physical (snap, surface roll, thread) or chemical (co-bonding, miscible) bonding.

In some places, it is called 2k injection molding. 2K injection molding (MSM) is by far the most versatile, complex and interesting of the MMM process. It requires a specific two-color injection molding machine to complete the injection molding. Plastic parts need to be molded twice, but the product is only ejection once, usually by a set of molds.