Plastic mold basic information

The DraftAngleAnalysis command visually evaluates surface draft-angle using false-color analysis.Draft angle is used to design injection-molded parts that must eject from molds.Steps1. Select objects.2. In the Draft Angle dialog box, set the angle for the color display.The draft angle depends on the construction plane orientation. When the surface is vertical/perpendicular to the construction plane, the draft angle is zero. When the surface is parallel to the construction plane, the draft angle is 90 degrees.3. Adjust the density of the mesh if the level of detail is not fine enough.Note● If you set the minimum and maximum angle to the same value, all portions of the surface that exceed the angle will be red.● The pull direction for DraftAngleAnalysis is the z-axis of the construction plane that is in the active viewport when the command starts.● The normal direction of the surface is the same as the pull direction of the mold. You can check this with the Dir command.● Changing the construction plane before using DraftAngleAnalysis lets you define any direction as the pull direction.

With the definition of the parting plane and all necessary shut-offs,the core insert and cavity insert have been completely separated.To create the cavity and core inserts,the length,width,and height of the inserts must be defined.All of these requirements suggest making the core and cavity inserts as large as possible.For smaller molded parts,increasing the sizing the core and cavity inserts may have little added cost. However,the cost of larger core and cavity inserts can become excessive with increases in the number of cavities or molded part size.The mold layout design assumes that the number of mold cavities and type of mold has been determined.To develop the mold layout, the mold opening direction and the location of the parting plane are first determined. Then, the length, width,and height of the core and cavity inserts are chosen. Afterwards,a mold base is selected and the inserts are placed in as simple and compact a layout as possible.It is important to develop a good mold layout design since later analysis assumes this layout design and these dimensions are quite expensive to change once the mold making process has begun.

Gate types The two main gate systems are manually trimmed gates and automatically trimmed gates. The following examples show where they are used:1. Sprue gate: Used for large components, the gate mark is visible in component and no runner is required. e.g.: bucket molding (backside cylindrical gate mark visible and can be felt).2. Edge gate: Most suitable for square, rectangular components3. Ring gate: Most suitable for cylindrical components to eliminate weld line defect4. Diaphragm gate: Most suitable for hollow, cylindrical components5. Tab gate: Most suitable for solid, thick components6. Submarine gate: Used when auto de-gating is required to reduce cycle time7. Reverse taper sprue gate (Pin gate): Generally used in three plate molds. 

Ejection system types l Pin ejection—Cylindrical pins eject the finished component. In the case of square and rectangular components, a minimum of four pins (at the four corners) are required. In the case of cylindrical components, three equidistant pins (i.e. 120° apart) are required. The number of pins required may vary based on the component profile, size and area of ejection. This ejection system leaves visible ejection marks on the finished component.l Sleeve ejection—This type of ejection is preferred for (and limited to) cylindrical cores, where the core is fixed in the bottom plate. In this system, the ejection assembly consists of a sleeve that slides over the core and ejects the component. No visible ejection marks are apparent on the component.l Stripper plate ejection—This ejection is preferred for components with larger areas. This system calls for an additional plate (stripper) between the core and cavity plates. To avoid flash, the stripper plate remains in contact with the cavity plate and a gap is maintained between the cavity and core plate. Visible ejection marks are usually not noted on components.l Blade ejection—This type of ejection is preferred for thin, rectangular cross sections. Rectangular blades are inserted in cylindrical pins (or cylindrical pins are machined to rectangular cross sections) to create an appropriate ejection length for the component. For easy accommodation of the ejection pin head, a counter bore is provided in the ejection plates.l By rotation of core (internal threaded components)—Used for threaded components, where the component is automatically ejected by rotating the core insert.l Air ejection—Used to actuate the ejection pin fitted in the core using compressed air. The ejection pin is retracted using a spring.

Hard Tooling -Steel/aluminum tools are used for the injection molding process for prototype or bridge, but these tools are mostly used for high volume production (100’s-100,000’s).-Steel/aluminum tools typically range in price from thousands to tens of thousands of dollars. And pending on the material and part geometry, the tool life can range from thousands to millions of parts. Soft Tooling -Silicone molds and the urethane process are used when a lower volume of parts is needed (1-100). This is because the tooling and piece price is more economical for lower quantities. On average, silicone tools usually cost in the hundreds to thousands of dollars, pending on the part geometry.-Silicone molds can be used for prototype, bridge and production of low volumes from one part to hundreds of parts. Most silicone molds are good for about 25 shots per cavity.

Hard Tooling -Steel/aluminum tools are used for the injection molding process for prototype or bridge, but these tools are mostly used for high volume production (100’s-100,000’s).-Steel/aluminum tools typically range in price from thousands to tens of thousands of dollars. And pending on the material and part geometry, the tool life can range from thousands to millions of parts. Soft Tooling -Silicone molds and the urethane process are used when a lower volume of parts is needed (1-100). This is because the tooling and piece price is more economical for lower quantities. On average, silicone tools usually cost in the hundreds to thousands of dollars, pending on the part geometry.-Silicone molds can be used for prototype, bridge and production of low volumes from one part to hundreds of parts. Most silicone molds are good for about 25 shots per cavity.