1. What is the commonly used plastics engineering materials and shrinkage ratio?
ABS::0.5%( Acrylonitrile Butadiene Styrene plastic--super non-breakable plastic);
PC:0.5%(Polycarbonate--Bulletproof glass plastic)
PMMA: 0.5%(Poly methyl methacrylate—Plexiglass)
PE: 2% (Polyethylene)
PS:0.5%( Polystyrene)
PP:2%( Polypropylene, )
PA：2%（Polyamide --Nylon)
PVC: 2% (Poly vinyl chloride)
Polyacetal（POM）:2%（Plug steel）
Acrylonitrile-butadiene-styrene+ Polycarbonate (ABS+PC):0.4%
Polycarbonate+ Acrylonitrile-butadiene-styrene：0.5%
2. What are the major systems for molding?
Pouring → Ejecting → Cooling → Forming → Exhausting
3. What problems shall be paid attention to during the process of mold design?
(1) The mold thickness shall be as uniform as possible and the demolding slope shall be large enough.
(2) The transition part should be done gradually. Sharp corners shall be prevented during smooth transaction.
(3)The Gate: The runner should be as wide as possible, thick and short. Meanwhile, the gate position should be set based on the shrinkage condensation process, and a cold well should be added if necessary.
(4) The surface of the mold should be smooth, with low roughness (preferably less;
(5)Vent holes and grooves must be sufficient to make sure air and gases in the melt can be discharged in time.
(6) Except for PET, the wall thickness should not be too thin, generally shall be ≥1mm.
4. What are the common defects in plastic parts?
Lack of glue→cloak→bubble→shrinkage→weld mark→black dots→stripe→lifting→Delaminating→peeling
5. What are the commonly used plastic mold steel?
45# S50c 718 738 718H
738H P20 2316 8407 H13
NAK80 NAK55 S136 S136H SKD61
6. Which type of materials can be used for high mirror polishing?
Using high-hardened & heat-treated steel in general, like SKD61, 8407, S136
7. What structures does mold base have?
Front plate→A plate→B Plate→Space plate→Guide pin→Ejector plate→Ejector retainer plate→Rear Plate
8. What are the basic forms of parting surface?
Straight→Slant→Curve→Alignment→Arc
9. How to hide each other in UG?
CtrL+ or Ctrl+shift+B
10. What are the mold processing machinery and equipment?
Computer Numerical Control (CNC) →Engine Lathe→ Milling Machine →Grinding Machine →Drilling Machine
11. What is 2D and 3D?
D is the abbr. for Dimension. 2D refers to a two-dimensional plane, while 3D refers to a three-dimensional space. In the mold industry, 2D usually refers to a plan view, i.e. a CAD drawing, and 3D usually refers to a three-dimensional view.
12. What is the default precision of pro/e and UG?
The default precision of pro/e is：0.0012MM, and for UG is 0.0254MM.
13. What are the he top four global mold base manufacturers?
Germany: HASCO; Japan: FUTABA (Futaba); United States: DME; China: LKM (Long Kee)
14. What is the default character height of CAD?
It’s 2.5MM.
15. What is kiss off and shut off?
The mating surface of the male and female mold parallel to the parting line is called the Kiss off. Then it's called as shut off if not parallel to the parting line.
16. What is the difference between Tiao and Si?
Both Tiao and Si are length units. Tiao is commonly used in Taiwan, 1 Tiao= 0.01mm. Si is used in Hong Kong, 1 Si= 0.01mm. Thus, 1 Tiao=1 Si
17. What is shut off?
There are often notches on the edge of the, which are used to install all kinds of accessories. The part of the pillow block formed here is called the shut off.
18. What is the Mold crater?
The shape of the reduced rubber part at the base of the BOOS column reflected on the mold after the eruption is called the mold crater.
19. What is Hezhi?
Hezhi refers to Mold core, HK slang.
20. What is the “Tiger’s Mouth”?
The tiger’s mouth is also called: the tube position, which is the part used to limit the position.
21. What is the mold layout?
The product layout on the mold is called mold layout.
22. What is the Glue position?
The cavity of the product on the mold is called: the glue position
23. What is the bone-positon?
The tendons on the product are called bone position.
24. What is the column positon?
The BOSS column on the product is called: column position.
25. What is the virtual position?
The gap on the mold is called: virtual position.
26. What is the buckle position?
The hook used for the product connection is called: buckle position.
27. What is the fire pattern?
The pattern left after EDM is called the fire pattern.
28. What is PL?
PL is also known as: parting surface, slap ramen, refers to the connection part between the front mold and the back mold when the mold is closed.
29. What is CNC?
It means Computer Numerical Control milling machine and machining center.
30. What is a copper worker?
EDM usually uses easy-to-process copper materials as discharge electrodes, which are called copper workers or electrodes. Copper workers are generally divided into rough workers, rough workers, young workers, and young workers, also called fine workers.
31. What is the spark gap in common?
During the discharge process, the discharge gap between copper and steel is called the spark level. Rough sparks are generally 0.1 to 0.5mm, and young sparks are generally 0.05 to 0.15mm.
32. What is the material level?
The avoidance of plastic products thickness is called the material level.
33. What is called the no wire cut?
The no wire cut is relative to the cutting insert. The no wire cut refers to a whole piece of steel as a processing blank, which is processed together during processing.
34. What is the Weld line?
The line formed by the meeting of two strands of plastic is called a weld line.
35. What is jet flow?
After the plastic enters the cavity from the plastic inlet, it forms a curved and folded snake-like flow mark called a jet flow.
36. What does LKM refers to?
LKM refers to the mold base of Longji group. Commonly used mold bases are: LKM, Fudeba, Mingli, Huansheng, Changhui, Desheng.
37. What does DME mean and what does HASCO mean?
Both DME and LKM are standards for standard products. DME is made in the US, while HASCO is made in Europe.
38. What is undercut?
The part of the product that cannot be directly demolded from the front and rear molds becomes an undercut.
39. What is fool-proof?
Fool-proof is an idiom, which is to prevent a very simple mistake and prevent a daze! For example: For example, if an insert is made with the same size hanging platform on the heaven and earth side, it is very likely that the heaven and earth side will be installed upside down during on-site assembly. But if he makes the hanging platform on the side of the insert, he couldn’t installed at all if the heaven and earth side is reversed, which is also impossible to put it wrong. This kind of action to prevent wrong actions from being in a daze becomes a fool-proof.
40. What is beer machine?
Beer machine is a local idiom, which is what we often call injection molding machine, molding machine.
41. What is called Zhikou?
The Zhikou is the art line, also known as the ugly-hidden line.
42. What is the flying model?
The flying model is the matching model or standard model.
43. What is light knife?
The action of CNC is called as light knife, which is to process in place on the basis of roughing.
44. What is the frame opening?
The action of processing the position of the mold core on the mold base is called frame opening.
45. What does Printed characters mean?
Printed characters are processed fonts that are placed on the film and then added to the font.
46. What is called Fanhe(reverse)?
The method of inverting the front and rear mold material positions under normal conditions to open the mold is called reverse.
47. What is called Floating?
The ejection method in which small inserts are used to eject the part where there is an undercut is called floating.
48. What is Cavity insert eating?
When the mold is opened, the product stays in the front mold is called the Cavity insert eating.
49. What is ejector mark?
When ejecting, the mold force required is relatively large, and the ejector pin is not strong enough, so that the product is partially ejected. From the front of the product, there is an obvious white as the top white, which is also called the top nozzle.
50. What is called as plate-burning?
The marks left by the entry point on the exterior surface of the system during diving are called plate-burning.
51. What is bolt?
The bolt is a clamping tool, a kind of cushion block with a triangular inclined surface opening slot.
52. What does overcutting mean?
Overcutting refers to excessive cutting, which means the parts that no need to be processed are also processed when processing the work piece. Overcutting is not good.
53. What is the calibration cup?
The Cavity insert pops out of the mold opening position.
54. What is Yata?
Tapping is called Yata.
55. When does a two-color molds need to be made?
When a product contains two different materials or different colors of the same material, a two-color mold is needed.
56. What is the mold design process of the factory?
Customers provide product drawings→analyze products→confirm plastic varieties→confirm mold material→transfer engineering drawings→make a mirror image by shrinking→perfect assembly drawings→order mold base→order mold core material→draft→3D parting→Determine the runner/gate method→Refer to the ranking drawing for structural design→Remove inserts→Correct 3D→Engineering drawing "Including: mold core/insert/mold blank/parts"→make BOM table→proof and review
57. How many ways are there for demolding?
Smoothed and forced demolding
58. What are the ways to feed glue?
Direct glue feeding → overlapping glue feeding → side glue feeding → ring feeding glue → sheet feeding glue → latent type → dispensing glue → horn feeding glue → fan feeding glue.
59. What are the forms of the runner?
Circular runner → semicircular runner → T-shaped runner → regular hexagonal runner.
60. What are the manuals and books for mold designers?
Steel books, plastic books, mold standard parts books.
61. What is the function of the spring?
Resilience when applied externally
62. Why is the mold need to be drafted?
Preventing the product from being strained when it is demolded.
63. What is the role of the screw and the determination of the matching length?
It is mainly used for tightening and fixing, and the mating length is generally 1.5 to 2 times the diameter of the screw.
64. What is the general slope of the slider, and what is the general slope of the oblique guide column?
The inclination of the slider is generally 20 degrees, and the inclination of the oblique guide column is generally 18 degrees.
65. What’s the function of cold slug well?
The function of the cold slug well is to store the small part of the plastic material with lower temperature that enters the mold first.
66. What’s the function of positioning ring?
The function of the positioning ring is to ensure the correct relative position between the mold and the injection machine.
67. What are the relative positions of the fit?
There are three main types of fit: clearance fit, transition fit, and interference fit.
68. What is the role of mold inserts?
It is convenient for processing, prevents carbon deposits, facilitates polishing, saves materials, helps exhaust, facilitates replacement, and reduces processing machines.
69. What are the indicators of hardness?
Hardness indicates the ability of a material to resist hard objects pressed into its surface. Commonly used hardness indicators are Brinell hardness, Rockwell hardness and Vickers hardness.
70. Can curved surface or group surface be drafted? And if the structural plane group can be replaced?
The curved surface cannot be drafted, the group surface can't. And the structural plane group can be replaced.
71. What is the difference between the first angle projection and the third angle projection?
① Where an object is placed in the first quadrant, the drawing method of projecting the view in the relationship of {viewpoint} (observer) → (object) → (projection surface) is called the first angle projection, also known as the first quadrant method.
②Where an object is placed in the third quadrant, the drawing method of projecting the view in the relationship of {viewpoint} (observer) → (projection surface) → (object) is called the third angle projection, also known as the third quadrant method.
Note: The difference between the first angle projection and the third angle projection is the article placed in the view.
The first angle painting projection: the left view is placed on the right, the right view is placed on the left, and the upper view is placed below, and so on…
The third angle projection: the left view is placed on the left, the right view is placed on the right, and the upper view is placed on top, and so on...
72. How many ways are there to transport water?
Commonly used water transports are: straight-through, surround, water tower, and spiral.
73. What are the basic principles of three views?
It refers to: the length is aligned, the height is flush, and the width is equal.
74. What are the types of injection machines?
According to the shape, there are vertical and horizontal injection machines (most commonly used). And if according to the injection volume, it is divided into ultra-small injection molding machine, small injection molding machine, medium injection molding machine, large injection molding machine, and super large injection molding machine, which is to say, the injection volume ranges from a few milligrams to tens of kilograms. And it's divided into several tons to several thousand tons based on the clamping force.
75. What is the relationship between clamping force and mold holding force?
The clamping force of the injection molding machine must be greater than the support force, otherwise the mold will be stretched by the pressure in the mold.
76. What are the positioning methods of male and female molds?
There are two types of positioning methods for the front and rear molds: one is mold positioning, and the other one is mold core positioning.
77. What is the appropriate wall thickness for commonly used plastics?
The appropriate wall thickness for ABS is1.8—3mm; for PC is2—3.5mm, and for POM is 1.5—2.5mm，while for NoryL is 2—3.5mm.
78. What is overflow value?
Overflow value refers to a value of how big a gap the plastic product will overflow, (that is, running burrs).The overflow for the following materials are:
ABS:0.04mm,PC:0.06mm,PA:0.015mm,POM:0.04mm,PBT+15%GR:0.03mm,PBT+30%:0.02mm,
PMMA:0.065mm,PVC:0.07mm,AS:0.05mm,PS:0.05mm,PP:0.03mm,PE:0.02mm.
79. How big is the standard frame?
Commonly used frames are: A0, A1, A2, A3, and A4.
The size for A0 frame is: 1189mx841m, for A1 frame is: 841mx594mm, and for A2 frame is: 594mmx420mm, A3 frame size is: 420mmx297mm, while for A4 frame is: 297mmx210mm.
80. What is the mold size planning?
Mold size standards vary from different companies. But the common standards are divided as follows: The molds of the 15-30 series mold bases are classified as small molds, and the 30-50 series mold bases are classified as medium molds, then it's called large molds if molds are of 50 or above.
81. What is elastic deformation? What is plastic deformation?
The object deforms under the action of external force. When the external force disappears, if the object can return to the original deformation before the deformation is called elastic deformation. Otherwise, it's called the plastic deformation.
82. What materials are commonly used for mold base?
Ace steel (called in Hong Kong, refers to S50C) is commonly used for mold base, which are medium carbon steel and 45 carbon steel.
83. What is the difference between CAD drawing work model space and layout space?
The model space is the space for graphic entities, and the layout space refers to the space of drawing layout.
84. What is the role of water transport?
The role of water transport is to control the temperature of the mold core.
85. What is a mold?
In industrial production, various presses and special tools installed on the press are used to make metal or non-metallic materials into parts or products of the required shape through pressure. Such special tools are collectively called molds.
86. What are the classification 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. According to the difference between the production process as well as the products, plastic molds can be divided into: Injection molding molds, blow molds, compression molding molds, transfer molding molds, extrusion molding molds, thermoforming molds and rotary molding molds. And if according to the different types of pouring system, molds can be divided into three categories: large nozzle molds, fine nozzle molds, and hot runner molds.
87. What is the pouring system?
The plastic flow channel from the nozzle of the injection machine to the cavity is called the pouring system. The pouring system includes the main runner, the runner, the gate and the cold slug well.
88. What is reverse engineering?
Reverse engineering is the accurate and high-speed scanning of the existing sample or model by a high-speed 3D laser scanner to obtain its 3D contour data, cooperate with the reverse software to reconstruct the curvature, and perform online accuracy analysis and evaluation of the reconstructed surface. The structure effect, the final IGES or STL data is generated, and the rapid prototyping or CNC machining can be performed according to the time. (CNC expert)
