Mold Design

The first thing of our DFM process is to check out the parts function, which will help clients to verify if the parts can function correctly. Our engineers will use 3D design software(Pro/e, Solidworks, UG) to simulate parts working condition. Meanwhile, we will check out if parts fitting and tolerance are reasonable.

If any design mistakes or imperfection found, we will provide design optimization report to clients. So that they can improve their design to have better final products.

Thickness of wall is one of the most important factor that affects the quality of injection molded products. Since an improper thickness of wall will result in parts shrinkage while injection molding process, on other hand, if a thick wall will increase parts weight that definitely increase part cost

During the DFM process, we will check out customer’s design drawing carefully. If any incorrect part thickness found, we will highlight them in the DFM report. So that our customer can notify and refine their product design.

Draft angle is used to make part release easily and smoothly when plastic injection molding, 0.5°~3.0° draft angle is needed for most of plastic parts, relatively to say, the deeper products requires to have more draft angle. For example, a 300mm-depth of rubbish bin requires about 2.0° draft, but a 800mm-depth of bin might need at least 4.0°~6.0° draft.

If a plastic part design without a draft, the molded parts will stick on injection mold and never be able to release.

While a DFM process, we will help to check out if customer’s design are well-added for draft angle. If not, we will report the problem so as to improve it before mold design.

Meanwhile, if needed, we can also directly help to add appropriate draft angle on parts.

In order to enhance plastic parts strength, it is necessary to add some ribs onto bosses, windows, platform, etc. However an improper thickness of ribs would result in shrinkage issue. A correct thickness of ribs will be 50%~75% of basic part thickness. For example, a part with 1.5mm of thickness of wall, the ribs should be designed as 0.75~1.13mm.

Our dedicating engineer will check 3D drawing carefully, and try to improve their design as proper as possible.

As we know, parts material will directly determine part function, cost, and quality. Because of different requirement, there will be many different choice for part material. A proper material choosing will help clients to save cost while not sacrificing part quality. If not, it might result money loosing and put project on risk. Our engineers have rich experience on plastic resin properties and application. We will suggest customers to use the best suitable plastic material while DFM.

Mold layout design is an overall planning work, which requires the mold designer to comprehensively realize mold cavity, gating type, parting line, ejection location, aesthetics surface, and potential molding defects. After those factors are resolved, our mold designer would create a mold specification sheet and 2D drawing for customer review.

At Inno molding, our experienced mold designers strive to work out best-optimized mold layout to save cost-saving and improve production efficiency and quality.

Parting line is one of the most common terminology of mold tool structure. It exists on molded parts surface, which ranging about 0.01~0.15mm in size.

A parting line can also be explained as the board line of mold core and cavity when mold tool closes and opens.

When injection mold design, it’s very important to design and choose a proper parting line, we should consider comprehensively for draft angle, mold open direction, parts assembly, appearance, and critical dimension control, In theory, we need to balance all of those factors and minimize the parting line as possible. Or you can say”no parting line” is the best “parting line” design.

A gating system refers to the whole channel through which the molten material flows to the mold cavity via injection machine. In the injection mold design process, designing a reasonable injection gate is one of the most important job, which defines where and which type of gate it should be. Because it not only just affects product appearance, production efficiency, but also it will directly affect manufacturing cost, as injection gate is a part of production scrap aspect.

Basically there are two main types of gating systems, which are manually trimmed gates and automatically trimmed gates. Generally speaking, manually trimmed gates include direct(or sprue) gate, side gate, tab gate; and automatically gates include banana gate, point gate, submarine gate, However manufacturing volume and parts requirements determines which type of gating system we should use.

As we know, a simple plastic part can be divided into mold core and cavity, where a parting line locates. However for some complex part structure, like screws, clippers, cutouts, pillars that exist on different direction while mold opening, it must be obtained via slider or lifter.

Mold slider and lifter can also be understood as a mechanism of a mold tool, which consists of forming surface, pull and push block(or cylinder), guide pin, and wedge. When mold opens and closes, the pull and push block work with wedge forth-and-back to obtain the desired part structure. This is how slider and lifter works basically.

When our mold design process, our experienced mold designer will design the most proper slider and lifter for those molds that requires them.

The cooling system of a plastic injection mold is designed to improve injection molding quality, production efficiency, and mold life-time, as well as reducing production scrap. Needless to say, it’s quite important to both mold making and injection molding process.

When we design a cooling system of injection mold, we will follow our principle as below:

• Try to make cooling system near the biggest thickness of products.
• Keep the cooling channel an appropriate distance from the parting line and products
• Try to increase the number of the cooling channel instead of enlarging the diameter of a single cooling channel.
• Try to keep the whole mold core or cavity cools evenly rather than partially cooling.

During the injection molding process, after mold cavity is fully injected with molten resin material, then the mold tool opens, and injection molded is pushed to depart from mold tool. This is how a ejection motion works.

An ejection system consists of ejection pin or block, basement of ejection system, a proper ejection system will need to fully consider product appearance, draft angle, and product length, because those factors will directly determines ejection type, size, and location.

Generally speaking, we minimize number of ejection points and ejection marks as long as the product can be smoothly depart from mold tool.