1. Common shrinkage of plastic materials?
ABS: shrinkage rate: 0.5%; use: it is material that can maintain dimensional accuracy of product, and it is generally used for products with high accuracy requirements, for example: ABS+PC is a commonly used material for mobile phone cases;
POM: Shrinkage: 2-5%; wear resistance and strength are very high, plastic gears are commonly used materials.
PS: Shrinkage: 0.5%; can be used as a transparent material, but it is relatively brittle and price is very cheap.
pp: Shrinkage: 1.6-20%; commonly used in occasions where size requirements are not high, such as car seats, these materials are basically used.
PMMA: Shrinkage: 0.4-0.6%, also known as plexiglass. It has high transparency and good light guide, but it is very easy to scratch. Tail lights on the car are made of PMMA.
PE: Shrinkage: 2-5%, commonly used for blow molding, generally used for soft gears.
PA: Shrinkage: 0.8-1.4%, very capricious, good strength.
PVC: Shrinkage: 1-2.5%; easy to aging, cheap price, now generally non-toxic PVC are used to make products.
PC: Shrinkage: 0.5-0.7%, high strength, high temperature resistance and expensive. Headlights on cars are made of this material.
MBS: Shrinkage: Like ABS, it is transparent ABS, but it is more brittle than ABS.
2. Frequent defects in plastic parts?
Lack of material, cloak, bubbles, shrinkage, weld marks, black spots, bubbles, stripes, warping, delamination, peeling, etc.
3. Commonly used plastic mold steel?
1.45——High-quality carbon structural steel, which is the most commonly used medium carbon quenched and tempered steel
2. Q235A (A3 steel)-the most commonly used carbon structural steel
3. 40Cr——one of the most widely used steel types, belonging to alloy structural steel
4. HT150-gray cast iron
5.35——Common materials for various standard parts and fasteners
6, 65Mn-commonly used spring steel
7. 0Cr18Ni9——The most commonly used stainless steel (US Steel 304, Japanese Steel SUS304)
8. Cr12——Commonly used cold work die steel (American Steel No. D3, Japanese Steel No. SKD1)
9, DC53-commonly used cold work die steel imported from Japan
10. Cr12MoV-wear-resistant chrome steel
11. SKD11-ductile chromium steel
12. D2——High carbon high chromium cold work steel
13, SKD11 (SLD)-non-deformation toughness high chromium steel
14, DC53-high toughness and high chromium steel
15. SKH-9——Universal high-speed steel with high wear resistance and toughness
16, ASP-23-powder metallurgy high-speed steel
17. P20——Generally required plastic mold
18, 718-high-demand plastic mold
19. NAK80——High mirror surface, high precision plastic mold
20. S136——Anti-corrosion and mirror polished plastic mold
21. H13——Commonly used die casting mold
22. SKD61-advanced die casting mold
23, 8407-advanced die casting mold
24, FDAC-added sulfur to enhance its ease of cutting
4. What kind of steel is used for high mirror polishing?
Commonly used high-hardness heat-treated steel, such as SKD61, 8407, S136, etc.!
5. What does mapping key do?
Simplify operation steps, reduce labor intensity and improve work efficiency!
6. What is difference between mirror body and mirror feature?
A: Mirror body refers to overall mirror image, and mirror image feature refers to local mirror image or single feature mirror image!
7. How to hide each other in UG?
CTRL+B and CTRL+SHIFT+B
8. Is there a local offset function in UG?
Yes
9. Does UG have a symmetry constraint function in sketching?
None
10. What is 2D? What is 3D?
D is prefix of English Dimension (line, dimension), 2D means two-dimensional space, and 3D means three-dimensional space. In mold part, 2D usually refers to a plan view, that is, a CAD drawing; 3D usually refers to a stereoscopic view, that is, a PRO/E, UG, or other 3D software drawing file.
11. What is default accuracy of PRO/E? What is default accuracy of UG?
Default precision of PRO/E is 0.0012MM, and default precision of UG is 0.0254MM
12. What is default character height of CAD?
Default character height of CAD is 2.5MM.
13. Where is CAD text file?
CAD text file is placed in Fonts folder under CAD root directory.
14. Does PRO/E have an automatic saving function like CAD?
PRO/E does not have an automatic save function.
15. What is bumping surface? What is inserting surface?
Fitting surface of male and female mold parallel to PL surface is called bumping surface; fitting surface of male and female mold not parallel to PL surface is called inserting surface!
16. Relationship between article and yarn?
Both article and the yarn are units of length. Article is for Taiwanese, 1 article = 0.01MM; yarn is for Hong Kong, 1 yarn= 0.01MM, so 1 article = 1 yarn
17. What is pillow position?
Edges of shell plastic parts are often notched, and are used to install various accessories. Pillow-shaped part formed here is called pillow position.

 

18. What is a mold crater?
A: Shape of BOSS column root reduced in plastic is reflected in mold similar to shape of volcanic eruption called mold crater.
19. What does “he” mean?
“He” is core, idiom in Hong Kong
20. What is a tiger's mouth?
Tiger mouth, also known as tube position, is used to limit part.
21. What is layout?
Product layout on mold is called layout.
22. What is inject position?
Cavity of product on the mold is called inject position.
23. What is bone position?
Ribs on product are called bone position.
24. What is column position?
BOSS column on product is called column position.
25. What is virtual position?
Gap on mold is called virtual position.
26. What is deduction?
Hook used for product connection is called buckle.
27. What is fire pattern?
Pattern left after EDM is called fire pattern.
28. What is PL surface?
PL is abbreviation of Parting Panel. PL is also called parting surface. It refers to part where male mold and female mold touch when mold is closed.
29. What is CNC?
Generic term for CNC milling machine and machining center.
30. What is a copper electrode?
EDM usually uses copper materials that are easy to process as discharge electrodes, called  copper electrode, also called electrodes. Copper electrode are generally divided into rough electrode, rough fine electrode, and fine electrode.
31. What is electrical discharge machining?
EDM is a self-excited discharge. Two electrodes of spark discharge have a higher voltage before discharge. When two electrodes are close, spark discharge occurs immediately after medium is broken down. Along with breakdown process, resistance between two electrodes suddenly decreases, and voltage between two electrodes also decreases sharply. Spark channel must be extinguished in a short time (usually 10-7-10-3s) in order to maintain "cold pole" characteristic of spark discharge (that is, heat energy of channel energy conversion is too late to reach electrode depth), so that channel energy acts on a very small range. Effect of channel energy can cause electrode to be locally corroded. Method of dimensional processing of materials by using corrosion phenomenon generated during spark discharge is called electrical discharge machining.
32. What is spark position?
During discharge process, discharge gap between copper electrode and steel is called spark position. Rough work spark position is generally 10 to 50, and fine work spark position is generally 5 to 15.
33. What is material position?
Thickness of plastic products is also called thickness.
34. What is original one?
Wish to stay is relative to cut inserts. Original stay means that a whole piece of steel material is processed into blank material, which is processed together during processing.
35. What are weld marks?
Line formed by encounter of two strands of plastic is called a weld mark.
36. What is a jet?
After plastic enters cavity from inlet, a flow mark that bends and folds like a snake is called a jet flow.
37. What does LKM mean?
LKM refers to Longji mold base. Commonly used mold base include LKM, Fubus, Mingli, Huansheng, Changhui, and Desheng.
38. What does DME mean? What does HASCO mean?
DME and LKM are both standard parts, DME is made in US, HSACO is made in Europe
39. What is undercut?
Part of product that male and female molds cannot be demolded directly is called undercut.
40. What is foolproof?
Foolproof is a idiom, which is to prevent very simple mistakes and prevent daze! For example: an insert has same size hanging platform on the side of heaven and earth. It is likely that side will be reversed during on-site assembly, but only one side of insert will be used as a hanging platform. It can't be installed, and it is impossible to install wrong one. This kind of action to prevent a daze and produce an error is called foolproof.
41. What is injection machine?
Injection machine is a local idiom, which is what we often say about injection molding machine and molding machine.
42. What is a stop?
Stop is jaw line, also known as ugly line.
43. What is fit mold?
Fit mold is matching mold.
44. What is a finish machining?
Action of CNC finishing is called finish machining, which means that it is processed in place on the basis of roughing.
45. What is build frame?
Action of processing position of mold core on mold base is called building frame.
46. What is texturing?
Texturing is processing method to do film and then add font.
47. What is anti-core?
Method of opening mold upside down under normal conditions is called reverse. For example, when mold of a toy car is opened, if shape of car is placed on the rear mold, it is an anti-core.
48. What is floating?
Method of ejecting small pop-ups is called floating.
49. What is pre-front mold?
When mold is opened, leaving product in front mold is called pre-front mold.

 

50. What is top white?
Ejection force required when ejecting is relatively large, and ejector pin is not strong enough, which causes product to be partially damaged. From front of product, phenomenon of obvious white or higher inject position is called top white, also called top high nozzle. .
51. What is bake printing?
Marks left on the appearance of product by water entry point during diving are called bake marks.
52. What is code?
Code is a clamping tool, a kind of cushion block with a triangular slanted opening.
53. What is overcutting?
Over-cutting refers to excessive cutting, that is, parts that do not need to be processed are also processed when processing the workpiece. Over-cutting is not good.
54. What is school cup?
Front mold pops up inside line of mold opening.
55. What is teeth clicks?
Tapping threads are called teeth clicks. Cantonese idioms.
56. What is a pitman?
Wrench used for tapping is called a pitman.
57. What is a beer handle?
Draft angle is called a beer handle, and Guangdong’s idiom.
58. When do I need to make a two-color mold?
When a product contains two different materials or same material with different colors, design a two-color mold to form!
59. Factory's mold design process?
Pre-molding meeting-analyzes product-transfer engineering drawing-2D layout-improve assembly drawing-the first pre-production meeting-corrects assembly drawing-mold base booking-mold material booking-3D parting-mold drafting, disassembly inserts-second pre-natal meeting-correct 3D core drawing-insert drawing-mold base drawing-mechanism drawing-BOM table
60. How to demold?
Smooth demold and forced demold!
61. Mold processing process?
See related information of mold processing process
62. What are ways of gate?
There are direct gate, lap gate, side gate, circular gate, sheet gate, latent gate, submerged eject gate, fish hook gate, point gate, etc.
63. What are forms of runners?
There are circular runner, semi-circular runner, T-shaped runner, positive hexagonal runner, etc.!
64. Standing manuals and books for mold designers?
Steel books, plastic books, mold standard parts books, etc.!
65. Common terms and expressions of mold parts and expressions in Chinese and English?
See relevant information of mold parts in Chinese and English.
66. What is role of springs?
Rebound force occurs when external force appears or elastic force occurs when external force disappears!
67. Why should mold be drafted?
Prevent product from being hurt when demoulding!
68. What are sky side, ground side, operator side, and counter operator side of mold?
Division of heaven and earth side is that mold is placed on injection molding machine. If mold is installed on injection molding machine, upper side is the sky side and lower side is the ground side.
Side operated by staff is called operating side, and the other side, which is away from operator, is called non-operating side or reverse operating side.
69. Role of screws and determination of mating length?
Screws are mainly used for fastening. Mating length is generally 1.5 to 2 times screw diameter.
70. Does N part of eject pin (double-section thimble) include height of eject head?
Yes!
71. How big is slope of inclined pin? What is slope of slider?
Slope of inclined pin is generally 7°±7°. Slope of slider is generally 18°±6°
72. Role of cold feed wells?
Role of cold feed well is to store small part of plastic material that enters mold first and has a relatively low temperature.
73. What is role of positioning ring?
Role of positioning ring is to ensure that correct relative position between mold and injection molding machine is maintained
74. What kind of coordination?
There are three main types of coordination: clearance coordination, transition coordination, and interference coordination.
75. What is role of inserts?
Convenient processing, preventing carbon deposition, conducive to polishing, saving materials, helping exhaust, easy replacement, shrinking processing machine, etc.
76. What are indexes of hardness?
Hardness indicates ability of a material to resist pressing of hard objects into its surface. Commonly used hardness indexes are Brinell hardness, Rockwell hardness and Vickers hardness.
77. Can surface be drafted? Can quilt be drafted? Can quilt be replaced?
Surface cannot be drawn. Quilt can be touched. Quilt can be replaced.
78. What is difference between first angle method and third angle method?
Method of projecting a view by placing object in the first quadrant and projecting view in the relationship of "viewpoint (observer)" → "object" → "projection plane" is called the first angle method, also known as the first quadrant method. Where object is placed in the third quadrant and view is projected in the relationship of "viewpoint (observer)" → "projection surface" → "object" is called the third angle method, also known as the third quadrant method.
Difference between the first angle drawing method and the third angle drawing method is position of view
First corner drawing: left view on the right, right view on the left, top view on the bottom, and so on.
Third triangle drawing: left view on the left, right view on the right, top view on top, and so on
79. How to transport water?
Common types include straight-through, orbital, water tower, and spiral.

 

80. What are basic principles of three views?
Basic principle of three views is long and straight, high and flush, and equal width.
81. What are parting methods of PRO/E?
There is copy surface for parting surface parting; parting surface for hole parting; side image + group side parting; volume block parting; component parting; manual parting. Among them, copying surface is most widely used as parting mode, and it is also the most effective.
82. What are types of injection molding machines?
According to shape, there are: vertical, horizontal, (most common); according to injection volume: ultra-small injection molding machine, small injection molding machine, medium injection molding machine, large injection molding machine, super large injection molding machine . That is, injection volume ranges from a few milligrams to tens of kilograms; according to clamping force, there are: several tons to several thousand tons.
83. How to calculate supporting force?
Mold support force (kg) = projected area of finished product in the direction of switch mold (cm2) * number of mold cavities * pressure in mold (kg/cm2);
84. What is relationship between clamping force and supporting force?
Clamping force of injection molding machine must be greater than supporting force, otherwise mold will be opened by pressure in the mold.
85. What are positioning methods for male and female mold?
A: There are two types of positioning methods for male and female molds: one is mold plate positioning, and the other is mold positioning.
86. What is appropriate wall thickness for commonly used plastics?
Suitable wall thickness of ABS is 1.8-3mm; suitable wall thickness of PC is 2-3.5mm; suitable wall thickness of PA is 2-3.5mm; suitable wall thickness of POM is 1.5-2.5mm; suitable wall thickness of NORYL It is 2-3.5 mm.
87. What is overflow value?
Overflow value refers to a value under which plastic product will overflow (that is, run off the edge). Overflow value of ABS is 0.04mm; overflow value of PC is 0.06mm; overflow value of PA is 0.015mm; appropriate wall thickness of POM is 0.04mm, and overflow value of PBT+15%GR is 0.03 mm; overflow value of PBT+30GR% is 0.02 mm; overflow value of PMMO is 0.065 mm; overflow value of PVC is 0.07 mm; overflow value of AS is 0.05 mm; overflow value of PS is 0.05 mm; overflow value of PP is 0.03 mm; overflow value of PE is 0.02 mm.
88. How big is standard frame?
Commonly used frames are A0, A1, A2, A3, A4. Size of A0 frame is 1188MM*840MM, size of A1 frame is 840MM*594MM, size of A2 frame is 594MM*420MM, size of A3 frame is 420MM-297MM, and size of A4 frame is 297MM*210MM.
89. Division of mold size.
Each company has different standards for dividing mold size, but common dividing standards are as follows: 15~30 series mold base are listed as small molds; 30~50 series mold bases are listed as medium molds; mold bases above 50 is classified as a large mold.
90. What is elastic deformation? What is plastic deformation?
Object deforms under action of external force. When external force disappears, object can return to shape before deformation is called elastic deformation; when external force disappears, object cant return to shape before deformation is called plastic deformation.
91. What materials are commonly used for mold base?
Ace steel (called in Hong Kong) is commonly used for mold bases. Ace steel is also medium carbon steel and 45# steel.
92. What is difference between CAD drawing work model space and layout space?
Model space is space for graphic entities, and layout space is space for layout of drawings.
93. What is polishing? What are commonly used polishing methods?
Act of improving surface finish of mold core is called polishing. Commonly used polishing methods include mechanical polishing; chemical polishing; electrolytic polishing; ultrasonic polishing; fluid polishing and magnetic abrasive polishing.
94. What is role of water transport?
Function of water transportation is to control temperature of mold core.
95. What is a mold?
In industrial production, various types of presses and special tools installed on press are used to make parts or products of desired shape from metal or non-metallic materials through pressure. These special tools are collectively called molds.
96. 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, die-casting molds, etc. Plastic molds are divided into injection molding molds, blow molds, compression molding molds, transfer molding molds, extrusion molding molds, thermoforming molds, rotary molding molds, etc. according to different production processes and products produced. 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.
97. What is reverse engineering?
Reverse engineering is accurate and high-speed scanning of existing sample or model by a high-speed 3D laser scanner to obtain its 3D contour data, use reverse software to reconstruct curvature, perform online accuracy analysis of reconstructed surface, evaluate construction effect, and finally generate IGES or STL data, which can be used for rapid prototyping or CNC machining.
98. What is exhaust groove? What is role of exhaust groove?
Groove on broken or scratched surface of mold core for exhaust is called exhaust groove. There are two main functions of exhaust groove: one is to remove air in mold cavity when molten material is injected; the other is to remove various gases generated during heating process of material.
99. What is gating system?
Plastic runner from injection nozzle to cavity is called gating system. Gating system includes main runner, branch runner, gate and cold slug well.
100. Pros and cons of hot mouth.
Advantages: 1. No nozzle material, no need for post-processing, making entire molding process fully automated, saving working time and improving work efficiency.
2. Pressure loss is small.
3. Repeated use of nozzle material will degrade performance of plastic, and use of hot runner system without nozzle material can reduce loss of raw materials, thereby reducing product costs.
4. Hot nozzle adopts standardized and serialized design, equipped with a variety of nozzle heads to choose from, and has good interchangeability.
Disadvantages: 1. Closing height of overall mold is increased, and overall height of mold is increased due to addition of hot runner plates.
2. Heat radiation is difficult to control. The biggest problem of hot runner is heat loss of runner, which is a major issue that needs to be solved.
3. There is thermal expansion, thermal expansion and contraction are issues that we must consider when designing.
4. Cost of mold manufacturing increases, and price of standard parts of hot runner system is higher, which affects popularity of hot runner molds.