01 Common plastic engineering materials and it’s shrinkage?
ABS: 0.5% (super broken plastic)
Pc: 0.5% (bulletproof glass plastic)
PMMa: 0.5%: (Plexiglas)
Pe: 2% (polyethylene)
PS: 0.5% (polystyrene)
Pp: 2% (100% soft rubber)
PA: 2% (nylon)
PVC: 2% (polyvinyl chloride)
POM: 2% (Sai Steel)
ABS+PC: 0.4%
PC+ABS: 0.5%
Engineering Materials: ABS PC PE POM PMMA PP PPO PS PET
02 What are major systems?
Pouring → ejector → cooling → forming → exhaust
03 What problems should I pay attention to during mold design process?
(1) Wall thickness should be as uniform as possible, and draft angle should be large enough.
(2) Transition part should be gradually and smoothly transitioned to prevent sharp corners.
(3) Gate. Runner should be as wide and thick as possible, gate position should be set according to shrinkage condensation process. If necessary, a cold well should be added.
(4) Surface of mold should be smooth and roughness is low (preferably 0.8)
(5) Venting holes, slots must be sufficient to exhaust air and gases in melt.
(6) Except for PET, wall thickness should not be too thin, generally not less than 1mm.
04 What are common occurrences of plastic parts?
Short Molding→cloak→bubble→shrinkage→welding mark→black spots→streak→lifting→layering→peeling
05 Commonly used plastic mold steel?
45# S50c 718 738 718H
738H P20 2316 8407 H13
NAK80 NAK55 S136 S136H SKD61
06 What kind of material is used for high mirror polishing?
Commonly used high-hardness heat-treated steel, such as: SKD61, 8407, S136
07 What are structures of mould base?
Panel → A plate → B plate → square iron → guide column → thimble plate → thimble fixed plate → bottom plate
08 What are basic forms of parting surface?
Straight → Tilt → Surface → Vertical → Arc Surface
09 How to hide from each other in UG?
ctrL+B or ctrL+shift+B
10 What are mold processing machinery?
CNC Machine→Lathe→Milling Machine→Grinding Machine→Drilling Machine
11 What is 2D and what is 3D?
English of D is: Dimension (line, dimension) prefix, 2D refers to two-dimensional plane, 3D refers to three-dimensional space. In mold part, 2D usually refers to a plan view, that is CAD drawing, and 3D usually refers to a perspective view.
12 What is default precision of pro/e and UG?
Default precision of pro/e is: 0.0012MM, and default accuracy of UG is 0.0254MM.
13 Top four enterprises in global mold base production?
Germany: HASCO Japan: FUTABA (Dual Leaf) USA: DME China: LKM (Long Ji)
14 What is default word height for CAD?
Default font height for CAD is: 2.5MM.
15 What is a k/o and what is a s/o?
Joint surface of male and female molds parallel to PL surface is called k/o, and surface of male and female molds that are not parallel to PL surface is called s/o.
16 Strip(tiao) and silk(si) relationship
Both strip and silk are length units, strip is Taiwanese, strip 1 = 0.01MM, silk from Hong Kong, 1 silk = 0.01MM, so 1 trip = 1 silk.
17 What is pillow position?
Edges of shell plastic parts are often notched and used to install various types of accessories. Part of pillow formed here is called pillow position.
18 What is crater?
Shape of BOSS column root thickness reduction that reflected on mold similar to shape of volcanic eruption called mold crater.
19 What is ke(core)?
Ke refers to core, Hong Kong idioms.
20 What is tiger mouth(inter lock)?
Tiger mouth is also called inter lock, which is part used for limit.
21 What is ranking?
Product layout on mold is called ranking.
22 What is seal position?
Cavity of product on mold is called: seal position.
23 What is bone position?
Tendons on product are called: bone position
24 What is a boss position?
Column of BOSS on the product is called: boss position.
25 What is virtual position?
Gap on mold is called: virtual position.
26 What is buckle?
Hook used to connect product is called: buckle.
27 What is EDM texture?
Texture left after EDM is called EDM texture.
28 What is PL surface?
PL surface is also called: parting surface and rake surface, which refers to part where front mold and rear mold are in contact when mold is closed.
29 What is CNC center?
CNC milling machine and machining center
30 What is copper electrode?
EDM usually uses easy-to-process copper material as discharge electrode. It is called copper electrode, also called electrode. Copper electrode is generally divided into: rough electrode and finish electrode.
31 What is spark gap usually?
During discharge process, discharge gap between copper electrode and steel materials is called spark gap, rough spark is generally 10 to 50, finish spark is generally 5 to 15.
32 What is material level?
Thickness of plastic products is also called thickness.
33 What is original body?
Original body is a piece of steel for processing of billet, processed together when processing.
34 What is weld line?
Line formed by encounter of two plastics is called a weld line.
35 What is jet?
Flow of plastic that forms a curved fold like a snake from gate into cavity is called a jet.
36 What does LKM mean?
LKM refers to longji mold base, commonly used mold bases are: LKM, Fu Deba, Mingli, Huansheng, Changhui, Desheng.
37 What does DME mean, what does HASCO mean?
DME and LKM are standards for standard parts, DME is made in US, and HASCO is made in Europe.
38 What is reverse buckle?
Part of product in which front and rear molds cannot be directly demolded becomes an inverted buckle.
39 What is foolproof?
Foolproof is a idiom that prevents a very simple mistake and a daze! For example, an insert has same size of hanging platform on the side of top and buttom. When assembling on site, it is very likely that side of top and buttom will be reversed, but he will make a hanging platform on one side of insert. If top and buttom side can't be loaded in opposite direction, it is impossible to install wrong one. This action to prevent occurrence of a daze and a mistake is a foolproof.
40 What is beer(injection) machine?
Beer(injection) machine is a local idiom, which is injection molding machine and molding machine we often say.
41 What is stop?
Stop is pinch art line, also known as ugly line.
42 What is a fit mould?
Fit Mould is matching mould.
43 What is finish machining?
CNC finishing motion is called finish machining, that is, it is machined in place on an rough basis.
44 What is open frame?
Action of machining position of mold core on mold base is called open frame.
45 What is texture?
Texture is processing font that is placed in film and then added to font.
46 What is reverse core?
Method of turning fount and rear mold position to open mold is called reverse core.
47 What is floating core?
Part that has a partial buckle with a small insert is called a floating core.
48 What is stuck in front mould ?
When mold is opened, product remains in front mold as stuck in front mould.
49 What is eject white?
When ejection is required, mold force is large, and thimble is not enough, so that product is partially broken. From front of product, there is obvious white for top white, which is also called top white.

 

50 What is baking?
Mark left on the surface of manufacturing point when diving into water is called baking.
51 What is clamp?
Clamp is a clamping tool, a pad with a triangular beveled open slot.
52 What is overcutting?
Overcutting refers to excessive cutting, that is, when workpiece is machined, parts that do not need to be machined are also processed, and overcutting is not good.
53 What is “xiaobei”?
Front mold pops up inner position of mold.
54 What is “yada”?
Tapping. Tapping thread is called “yada”.
55 When do you need to make a two-color mold?
Design a two-color mold when a product contains two different materials or different colors from same material.
56 What is mold design process for factory?
Customer provides product drawing → analysis product → confirm plastic variety → confirm mold material → transfer engineering drawing → take shrinking as mirror phase → perfect group diagram → order mold base → order mold material → extract mold → 3D mold split → determine runner /Gate type→Structure design with reference to layout diagram→remove inserting→Correct 3D→Project drawing “Including: core/insert/mold base/Parts”→Do BOM → proofreading
57 How many ways to demould?
Smooth and forced demolding
58 What are feeding methods?
Direct Gate → Tab Gate→ Side Gate → Ring Gate → Film Gate → Submarine Gate → Pin Point Gate → Banana Gate → Fan Gate.
59 What are forms of runner?
There are circular runner → semi-circular runner → T-shaped runner → regular hexagonal runner.
60 Mold designers' standing manuals and books?
Steel books, plastic books, mold standard parts books.
61 What is role of spring?
Resilience occurs when external use occurs
62 Why should mold be drafted?
Prevents product from being pulled when it is released.
63 What is role of screw and length of fit?
Mainly tightening and fixing, matching length is generally 1.5 to 2 times diameter of screw.
64 How large is slope of slider, and how large is slope of inclined guide column?
Slope of slider is generally taken as 20 degrees, and slope of inclined guide column is generally 18 degrees.
65 Role of cold wells?
Function of cold well is to store a small portion of lower temperature plastic material that first enters mold.
66 What is role of positioning ring?
Purpose of positioning ring is to ensure that correct relative position between mold and injection machine is maintained.
67 Relative position of fit?
Fit is mainly divided into three categories: clearance fit, transition fir, and interference fit.
68 What is role of insert?
Convenient processing, preventing carbon deposits, facilitating polishing, saving materials, helping to vent, facilitating replacement, and reducing processing machines.
69 What are indicators of hardness?
Hardness indicates ability of a material to resist intrusion of a hard object into its surface. Commonly used hardness indexes are Brinell hardness, Rockwell hardness and Vickers hardness.
70 Can curved surface be drafted? Can group surface be drafted? Can quilt be replaced?
Curved surface can not be drafted, group surface can be drafted, and quilt can be replaced.
71 What is difference between first angle method and third angle method?
1. When placing an object in the first quadrant, method of projecting view by relationship of {viewpoint} (observer) → (object) → (projection surface) is called first angle method, also known as first quadrant method.
2. Where object is placed in the third quadrant, drawing method is projected by {viewpoint} (observer) → (projection surface) → (object) relationship, which is called third angle method, also known as third quadrant method. .
Note: Difference between first angle drawing and third corner drawing is article placed by view.
First angle drawing: left view is placed on the right, right view is placed on the left, upper view is placed below, and so on...
Third angle drawing: left view is placed on the left, right view is placed on the right, upper view is placed on the top, and so on...
72 What are ways of water line?
Commonly used for water line are: straight-through, wraparound, water tower, and spiral.
73 What are basic principles of three views?
Basic principle of three views is: long alignment, high level and width.
74 What are types of injection machines?
According to shape; vertical, horizontal. The two most commonly used injection volume is divided into: ultra-small injection molding machine, small injection molding machine, medium-sized 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, and is divided into several to several thousand tons according to clamping force.
75 What is relationship between clamping force and supporting force?
Clamping force of injection molding machine is greater than supporting force, otherwise mold will open cause pressure inside mold.
76 What are positioning methods of male and female molds?
There are two types of positioning methods for front and rear molds. One is template positioning, and the other is: core positioning.
What is appropriate wall thickness for commonly used plastics?
Suitable wall thickness of ABS is: 1.8-3mm, PC is: 2-3.5mm, POM is: 1.5-2.5mm, NoryL is: 2-3.5mm
78 What is overflow value?
Overflow value refers to value of plastic product that overflows under gap. Overflow value of ABS is 0.04mm, pc is 0.06mm, PA is 0.015mm, POM is 0.04mm, PBT+15%GR is 0.03mm, PBT+30% is: 002mm, PMMA is 0.065mm, PVC is 0.07mm, AS is 0.05mm, ps is 0.05mm, pp is 0.03mm, PE is: 0.02mm.
79 What is standard frame?
Commonly used frames are: A0, A1, A2, A3, A4, A0 frame size is: 1189mx841m, A1 is: 841mx594mm, A2 is: 594mmx420mm, A3 is 420mmx297mm, and A4 is 297mmx210mm.
80 Planning of mold size?
Each company's planning mold size standards are different, but common standards are divided as follows: 15-30 series mold base are listed as small molds, 30-50 series are listed as medium molds, 50 or more are listed as large mold.
81 What is elastic deformation? What is plastic deformation?
Object is deformed under action of external force. When external force disappears, deformation that can restore to state before deformation is called elastic deformation. Otherwise is called plastic deformation.
82 What materials are commonly used in mold base?
Mold base commonly use ace steel, also named medium carbon steel, 45 steel.
83 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 drawing layout.
84 What is role of water line?
Role of water line is to control temperature of core.
85 What is molding?
In industrial production, metal or non-metal materials are used to produce parts or articles of a desired shape by pressure using various presses and special tools mounted on press. These special tools are collectively referred to as molding.
86 Classification of molds?
Molds can be generally divided into plastic molds and non-plastic molds. Non-plastic molds include: casting molds, forging molds, stamping molds, die-casting molds. Plastic molds are further divided into injection molding molds, air blowing molds, compression molding molds, transfer molding molds, extrusion molding molds, thermoforming molds, and rotary molding molds. According to different production types of casting system, mold can be divided into three categories: big nozzle mold, Fine nozzle mold, hot runner mold.
87 What is a gating system?
Plastic flow path from injection nozzle to cavity is called gating system. Gating system includes: main flow, split runner, gate and cold well.
88 What is reverse engineering?
Reverse engineering is an accurate and high-speed scanning of existing samples or models by high-speed 3D laser scanner, its 3D contour data is obtained, software is reconstructed with reverse software. Online precision analysis and evaluation of reconstructed surface are carried out, and finally generation of IGES or STL data can be performed by rapid prototyping or CNC numerical control processing.