1. What are the main systems of a mold?

Gating → Ejection → Cooling → Molding → Venting.

2. What issues should be considered during mold design?

(1) The wall thickness should be as uniform as possible, and the draft angle should be sufficiently large.

(2) Transitions should be gradual and smooth, avoiding sharp corners.

(3) Gates: Runners should be as wide and short as possible, and their positions should be determined based on the shrinkage and solidification process. Cold slug wells should be added if necessary.

(4) The mold surface should be smooth with low roughness (preferably below 0.8).

(5) Venting holes and channels must be sufficient to allow for timely removal of air and gases from the melt.

(6) Except for PET, the wall thickness should not be too thin, generally not less than 1mm.

3. Common defects in plastic parts?

Insufficient injection → burrs → bubbles → shrinkage → weld lines → black spots → streaks → lifting → delamination → peeling.

4. What are the structural components of the mold base?

Face panel → A plate → B plate → Square iron → Guide pillars → Ejector plate → Ejector fixing plate → Base plate.

5. What are the basic forms of parting surfaces?

Straight → Inclined → Curved → Vertical → Arc-shaped

6. What are the types of mold processing machinery and equipment?

CNC milling machine → lathe → milling machine → grinding machine → drilling machine.

7. What is a through-hole and what is an insert-hole?

The mating surface of the male and female molds that is parallel to the PL surface is called the through-hole surface, and the mating surface of the male and female molds that is not parallel to the PL surface is called the insert-hole surface.

8. What is a weld line?

A weld line is the line formed when two strands of plastic meet.

9. What is flow mark?

Flow mark refers to the wavy, snake-like pattern formed when plastic enters the mold cavity from the sprue.

10. What is an undercut?

An undercut is a part of a product that cannot be directly demolded from the front and rear molds.

11. What is ejector white?

When ejection requires a large mold force, and the ejector pins are not strong enough, the product is damaged in a localized area. This is called ejector white, also known as high ejector gate, and is visible as a distinct white area when viewed from the front.

12. What is the mold design process in a factory?

Customer provides product drawing → Product analysis → Confirm plastic type → Confirm mold material → Convert to engineering drawing → Perform mirror image based on shrinkage → Refine assembly drawing → Order mold blank → Order mold core material → Drafting → 3D mold parting → Determine runner/gate method → Perform structural design based on layout drawing → Remove inserts → Correct 3D → Engineering drawings (including mold core/inserts/mold blank/disassembled parts) → Create BOM (Bill of Materials) → Proofreading and approval.

13. What are the different gate injection methods?

Direct injection → Overlap injection → Side injection → Circular injection → Thin sheet injection → Submerged injection → Dot injection → Horn-shaped injection → Fan-shaped injection

14. What are the classifications of molds?

Molds can generally be divided into plastic molds and non-plastic molds. Non-plastic molds include: casting molds, forging molds, stamping molds, and die-casting molds. Plastic molds are further classified according to the production process and the product being produced: injection molding molds, blow molding molds, compression molding molds, transfer molding molds, extrusion molding molds, thermoforming molds, and rotational molding molds. Based on the type of gating system, molds can be divided into three categories: large-gate molds, small-gate molds, and hot runner molds.

15. What is a gating system?

The plastic flow path from the injection nozzle to the mold cavity is called the gating system. The gating system includes: main runner, branch runners, gate, and cold slug well.

16. What is elastic deformation? What is plastic deformation?

When an object deforms under the action of an external force, and the object returns to its original shape after the force is removed, this is called elastic deformation. When the external force is removed, the object cannot return to its original shape, this is called plastic deformation.

17. What are the positioning methods for male and female molds?

There are two types of positioning methods for front and rear molds: one is template positioning, and the other is mold core positioning.

18. Mold size planning?

Each company has different standards for planning mold size, but common standards are as follows: molds with mold blanks of 15-30 series are classified as small molds, molds with mold blanks of 30-50 series are classified as medium molds, and molds with mold blanks of 50 and above are classified as large molds.

19. What is reverse engineering?

Reverse engineering involves using a high-speed 3D laser scanner to accurately and rapidly scan an existing sample or model to obtain its 3D contour data. This data is then used in conjunction with reverse engineering software to reconstruct the surface, perform online accuracy analysis of the reconstructed surface, evaluate the construction effect, and ultimately generate IGES or STL data. Based on this data, rapid prototyping or CNC machining can be performed.

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