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Faqs on 100 CNC Molding Design and CNC Precision Machining

Posted by: Fymicohuang 2021-10-07 Comments Off on Faqs on 100 CNC Molding Design and CNC Precision Machining

1.What is the commonly used shrinkage rate of plastic materials?

Answer: ABS shrinkage rate: 0.5%;Application: it is the most accurate material to maintain the product size. Generally, it is used in products with high accuracy requirements. For example, ABS+PC is a common material for mobile phone shell.POM shrinkage: 2-5%, wear resistance and strength are very high, plastic gear are commonly used materials.PS shrinkage rate: 0.5% can do transparent material, but more brittle, but the price is very cheap.Pp shrinkage rate: 1.6-20%;It is commonly used in places where the size requirements are not high, such as car seats, are basically made of these materials.PMMA shrinkage rate: 0.4-0.6%, also known as plexiglass, transparent performance is high, good light conductivity, but easy to scratch, car taillights are PMMA do.PE shrinkage rate: 2-5%, commonly used blow molding, generally do soft gear.PA shrinkage rate: 0.8-1.4%, high toughness and good strength.PVC shrinkage: 1-2.5%;Easy to aging, the price is cheap, generally is to do with non-toxic PVC products.PC shrinkage rate: 0.5-0.7%, high strength, high temperature resistance, the price is not cheap.Headlights on cars are made of this material.MBS shrinkage rate: transparent ABS is the same as ABS, but less brittle than ABS.
2. What faults are often detected in plastics?

Answer:Lack of glue, cape, bubble, shrinkage, fusion mark, black spot, bubble, stripe, warping, lamination, peeling, etc.

3.What are the commonly used plastic mold steels?

Answer: 1, 45 — high-quality carbon structural steel, is the most commonly used carbon quenched steel 2, Q235A(A3 steel) — the most commonly used carbon structural steel 3, 40Cr — one of the most widely used steel, belongs to the alloy structural steel 4, HT150 — gray cast iron 5, 35 — common materials for various standard parts and fasteners 6, 65Mn — common spring steel7, 0Cr18Ni9 — most commonly used stainless steel (304 USA steel, 304 Japan steel SUS304)8, Cr12 — commonly used cold work die steel (D3 USA steel, SKD1 Japan steel)9, DC53 — commonly used cold work die steel imported from Japan 10, Cr12MoV — wear-resistant chromium steel 11, SKD11 — ductile chromium steel 12, D2 — high carbon and high chromium cold working steel

13, SKD11(SLD) — non-deforming toughness high-chromium steel 14, DC53 — high toughness high-chromium steel 15, SKH-9 — wear resistance, high toughness general purpose high-speed steel 16, ASP-23 — powder metallurgy high-speed steel 17, P20 — general requirements of the size of plastic mold 18, 718 — high requirements of the size of plastic mold 20, S136 — Anti-corrosion and plastic molds requiring mirror polishing 21, H13 — commonly used die casting molds 22. SKD61 — Advanced die casting mould 23, 8407 — Advanced die casting mould 24, FDAC — sulfur is added to enhance its sharpness.

  1. What kind of steel is used for high mirror polishing?

Answer:Commonly used high – hard heat treatment steel, such as SKD61, 8407, S136 and so on.

  1. What does a mapping key do?

Answer:Simplify operation steps, reduce labor intensity and improve work efficiency.

  1. What is the difference between a mirror image and a mirror image?

Answer:The mirror image refers to the whole mirror image, and the mirror image refers to the local mirror image or the single characteristic mirror image.

  1. 在UG中如何互相隐藏?How do you hide each other in UG?

Answer: CTRL+B and CTRL+SHIFT+B

  1. Is there local bias in UG?

Answer: Yes.
9. Does UG have symmetric constraint function in sketching?

Answer:No.

  1. What is the 2D and 3D.

Answer:D is the prefix of English Dimension, 2D refers to two-dimensional plane and 3D refers to three-dimensional space.In the mold section, 2D is usually a plane, or CAD drawing;3d usually refers to a stereogram, i.e. a PRO/E, UG or other 3D software file.

  1. What is the default accuracy of PRO/E? What is the default precision for UG?

Answer:The default precision for PRO/E is 0.0012mm and UG is 0.0254mm.

  1. What is the default character height in CAD?

Answer:The CAD default word height is 2.5mm

  1. Where do you put the CAD text files?

Answer:Fonts for CAD text files are placed in the CAD root folder.

  1. Does PRO/E have an auto-save feature like CAD?

PRO/E has no auto-save feature

  1. What is a bump? What is a plug?

Answer:The bonding surface of the male and female die parallel to the PL surface is called the contact penetrating surface.The mating surface of the male and female die that is not equal to the PL surface is called the piercing surface.

  1. The relationship between the bar and the silk?

Answer:Strips and silk are units of length.For Taiwan, 1 = 0.01mm;Silk is the Hong Kong term, 1 silk =0.01MM, so, 1 =1 silk.

  1. What is the occipital position?

Answer:The edge of shell type plastic piece often has a gap, used for installing all kinds of accessories, the pillow shaped parting part formed here is called the pillow position.

  1. What is a crater?

Answer:The BOOS column root is partially reflected in the mold in a shape similar to that of an erupting volcano, called the mold crater.

  1. What does it mean?

Answer:Ah is the model benevolence, Hong Kong idiom

  1. What is a tiger mouth?

Answer:The tiger’s mouth, also known as the pipe position, is used to limit the part.

  1. What is ranking?

Answer:The product layout on the mold is called the rank

  1. What is a glue position?

Answer:The product layout on the mold is called the rank

  1. What is called bone position?

Answer:The tendon on the product is called the bone position

  1. What is a column position?

Answer:The BOSS column on the product is called a column
25. What is virtual bit?

The gap on the die is called virtual bit.

  1. What is the buckle?

The hook used for product connection is called buckle position

  1. What is fire pattern?

The pattern left after edM is called fire pattern.

  1. PL, which is short for Parting Panel, is also called Parting surface, which means the part in which the male pattern and the female pattern touch when the mold is closed..
  2. What is a computer gong?

General name of CNC milling machine and machining center..
30. What is a coppersmith?

Answer: edM usually USES the copper material which is easy to process to make the discharge electrode, called copper work, also known as the electrode. Copper work is generally divided into coarse work, coarse young work, young work. Young gong also known as seiko.
31. What is discharge machining?

Answer: Electric spark is a kind of self-excited discharge. The two electrodes of spark discharge have a high voltage before discharge, when the two electrodes approach, the medium between them is broken down, then spark discharge occurs. Along with the breakdown process, the resistance between the two electrodes decreases sharply, and the voltage between the electrodes also decreases sharply. The spark channel must be extinguished in time after being maintained for a short period of time (usually 10-7-10-3s) to maintain the “cold pole” characteristics of the spark discharge (i.e., the heat energy of the channel energy conversion does not reach the depth of the electrode in time), allowing the channel energy to be applied over a very small range. The effect of channel energy can cause the electrode to be corroded locally. The method that the corrosion phenomenon that produces when using spark discharge undertakes dimensional machining to the material is called electric spark machining.

  1. What is the spark bit usually?

Answer: in discharging process, the discharge gap between copper and steel is called spark bit. The rough spark spots are usually between 10 and 50, and the young spark spots are usually between 5 and 15.

  1. What is the stock level?

Answer:  the wall thickness of plastic products, also known as meat thickness.

  1. What is the original body?

Answer: wish the body stays is opposite with cut insert character, original body stays is to show a whole piece of steel makings is processing blank makings, when processing, process together come out.

  1. What is the weld mark?

Answer: the line that two plastics meet to form is called weld mark.

  1. What is a jet?

Answer:The flow marks formed by the curved folding of the plastic into the cavity from the inlet are called jets.

  1. What is an LKM?

Answer:LKM refers to the dragon memory mould. Common models include LKM, Fuba, Minli, Huansheng, Changhui, Desheng, etc.

  1. What does DME mean? What does HASCO mean?

Answer:BOTH DME and LKM are standard parts. DME is made in the United States and HSACO is made in Europe.

  1. What is inversion?

Answer: The part in the product where the male mold can not be directly demoulded is called the reverse.

  1. What is anti-stupor?

Answer: prevent to stay is a kind of idiomatic expression, prevent to appear namely very simple mistake, prevent to be in a daze. For example, when a panel is mounted on the side of heaven and earth, it is likely to mount the side of heaven and earth upside down when it is assembled on site, but it is only mounted on one side of the panel. At this time, if the panel is mounted on the side of heaven and earth upside down, it is impossible to mount the wrong one. This action to prevent the occurrence of a trance and the generation of mistakes is called anti-stupor.

  1. What is a beer machine?

Answer:Beer machine is a local idiom, that is, we often say injection molding machine, molding machine.

  1. What is a stop?

Answer: stop mouth is clip mouth art line, also called cover ugly line.

  1. What is flying die?

Answer: flying die is to match die

  1. What is a light knife?

Answer: the action of CNC finishing is called polishing knife, that is, on the basis of the rough machining in place.

  1. What is open box?

Answer:The action of processing the position of the mould kernel on the mould blank is called opening frame.

  1. What do you mean by airing characters?

Answer: the sun is to do a good job of film and then take the font processing method.

  1. What is invert?

Answer: will be normal before and after the die level upside down die method is called inverse ah. For example, when the mold of a toy car is opened, it belongs to anti-offset if the outside surface of the car is put into the mold.

  1. What is floating?

Answer: the place that local has upside-down USES small insert to pop out die method to be called float.

  1. What is eating front mold?

Answer:When the die is opened, the product is left in the front die called the eat front die.

50.What is top white?
Answer: The ejection force required for ejection is large, and the ejector pin is not strong enough, which makes the product partially damaged. From the front of the product, there is obvious white or the phenomenon of higher glue level is called top white, also called top nozzle .

51. What is baking mark?
Answer: The mark left by the water entry point on the surface of the product during diving is called baking.
52. What is a code boy?
Answer: The code is a clamping tool, a kind of cushion block with a triangular inclined surface to open the buckle slot.
53. What is Over-Cutting?
Answer: Over-Cutting refers to excessive cutting, that is, the parts that do not need to be processed are also processed when processing the workpiece. Over-Cutting is not good.
54.What is the school cup? Answer: the front die pops out the inside position of the open die.

55. What is a tooth tap? Answer: Tapping thread, tapping thread is called tooth tap.

56. What is a pit hand? Answer: The wrench used for tapping is called a pitman.

57. What is beer? Answer: tilting die is called beer.
58. When do I need to make a two-color mold? Answer: When a product contains two different materials or different colors of the same material, design a two-color mold to form
59. Tooling design process in the factory? Answer: the meeting before mold opening: analyze the 2D layout of the product transfer drawing and improve the assembly drawing;The first pre – production meeting: correct assembly drawing, mould blank, mould kernel material, 3D parting, mould drawing, and insert removal;The second prenatal meeting: correct the 3D mold kernel drawing, insert drawing, mold embryo drawing, mechanism drawing, and make BOM.
60. How many ways to demoulder? Answer: smooth and strong.
61. Tooling process flow? Answer: (See related information about mold processing process flow)
62. What are the injection methods? Answer: there is a direct adhesive lap into adhesive side of the adhesive ring moving adhesive sheet into adhesive latent adhesive thimble into adhesive fishing hook into the adhesive needle point into adhesive
63. What are the flow channels? Answer: have circular runner semicircular runner T – shaped runner is hexagonal runner
64. Regular manuals and books for mold designers? Answer: Steel books, plastic books, mold standard parts books, etc.
65. Common terms and Expressions in English and Chinese for mold parts? Answer :(see relevant information in both Chinese and English for mold parts)
66. What is the function of a spring?
67. Why should the mold be drawn? Answer: Prevent the product from being strained when it is demoulded.
68. What are the sky side, ground side, operator side and anti-operator side of the mold? Answer: The division of the sky and the earth is based on the fact that the mold is placed on the injection molding machine, and the mold is installed on the injection molding machine. The side operated by the staff is called the operating side, and the other side that is away from the operator is called the non-operating side or the counter-operating side.
69. How to determine the function and fit length of screws? Answer: The screws are mainly used for fastening. The mating length is generally 1.5 to 2 times the screw diameter.
70. Do N parts with a thimble include the height of the thimble head? Answer: Yes.
71. What is the slope of the diagonal pin? What is the slope of the slider? Answer: The inclination of the diagonal pin is generally 7°±7°. The slope of the slider is generally 18°±6°.
72. The role of cold feed Wells? Answer: The function of the cold material well is to store the small part of the plastic material with lower temperature that enters the mold first.
73. What is the role of the positioning ring? Answer: The function of the positioning ring is to ensure the correct relative position between the mold and the injection molding machine.
74. What kind of coordination? Answer: The fit is mainly divided into three categories: clearance fit, transition fit, and interference fit.
75. What is the function of the insert? Answer: It is convenient for processing, prevents carbon deposits, facilitates polishing, saves materials, helps exhaust gas, facilitates replacement, and reduces processing machines.
76.What kinds of hardness indexes are there? Answer: Hardness refers to 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.
77. Can the surface be moulded? Can the panel be drawn? Can a face group be replaced? Answer: the surface can not be drawn. Face sets can be pulled out. Face sets can be replaced.
78. What is the difference between the first corner and the third corner? Answer: When placing an object in the first quadrant and projecting the view in the relationship of “viewpoint (observer)” → “object” → “projection surface”, it is called the first angle method. Also known as the first quadrant method. Where an object is placed in the third quadrant and the view is projected in the relationship of “viewpoint (observer)” → “projection surface” → “object”, it is called the third angle method. Also known as the third quadrant method.

The difference between the first angle painting and the third angle painting is the position of the view. The first corner painting method: the left view is placed on the right, the right view is placed on the left, the upper view is placed below, and so on. The third triangle drawing method: the left view is placed on the left, the right view is placed on the right, the upper view is placed on the top, and so on.
79. How many ways to transport water? Answer: The common ones are straight-through, wrap-around, water tower, spiral, etc.
80. What are the basic principles of the three views? Answer: The basic principle of three views is that the length is right, the height is even, and the width is equal.
81. What are the parting methods of PRO/E? Answer: There is a copy surface for parting surface parting; there is a parting surface to fill holes and parting; there is silhouette + group edge parting; there is volume block parting; there is component parting; there is manual parting. Among them, the copy surface is the most widely used as parting surface and the most effective.
82. What kinds of injection molding machines are there? Answer: According to the shape, there are: vertical, horizontal, (the two most common); according to the 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, the injection volume ranges from a few milligrams to tens of kilograms; according to the clamping force, there are: several tons to several thousand tons.
83. How to calculate the bracing force? Answer: Die supporting force (kg) = Projected area of ​​finished product in the direction of opening and closing die (cm2) × number of mold cavities × pressure in mold (kg/cm2)
84. What is the relationship between clamping force and clamping force? Answer: The clamping force of the injection molding machine must be greater than the supporting force, otherwise the mold will be opened by the pressure in the mold.
85. What are the ways to locate male and female molds? Answer: There are two types of positioning methods for male and female molds: one is template positioning, and the other is mold core positioning.
86. What is the appropriate wall thickness for commonly used plastics? Answer: The suitable wall thickness of ABS is 1.8-3mm; the suitable wall thickness of PC is 2-3.5mm; the suitable wall thickness of PA is 2-3.5mm; the suitable wall thickness of POM is 1.5-2.5mm; the suitable wall thickness of NORYL It is 2-3.5 mm.
87. What is overflow value? Answer: The overflow value refers to a value that the plastic product will overflow (that is, run off) under the gap. The overflow value of ABS is 0.04mm; the overflow value of PC is 0.06mm; the overflow value of PA is 0.015mm; the appropriate wall thickness of POM is 0.04mm, and the overflow value of PBT+15%GR is 0.03 mm; PBT The overflow value of +30GR% is 0.02 mm; the overflow value of PMMO is 0.065 mm; the overflow value of PVC is 0.07 mm; the overflow value of AS is 0.05 mm; the overflow value of PS is 0.05 mm; the overflow value of PP The edge value is 0.03 mm; the overflow edge value of PE is 0.02 mm.
88. How big is the standard drawing frame? Answer: The commonly used frames are A0, A1, A2, A3, A4. The size of A0 frame is 1188MM*840MM, the size of A1 frame is 840MM*594MM, the size of A2 frame is 594MM*420MM, the size of A3 frame is 420MM-297MM, and the size of A4 frame is 297MM*210MM.
89. Mold size division. Answer: Each company has different standards for dividing the mold size, but the common division standards are as follows: 15~30 series mold base molds are listed as small molds; 30~50 series mold bases are listed as medium molds; mold bases above 50 The mold is classified as a large mold.
90. What is elastic deformation? What is plastic deformation? Answer: The object deforms under the action of external force. When the external force disappears, the object can return to the deformation before the deformation is called elastic deformation; when the external force disappears, the deformation of the object before the deformation is called plastic deformation.
91. What materials are commonly used in molds? Answer: Ace steel (called in Hong Kong) is commonly used for mold blanks. Ace steel is also medium carbon steel and 45# steel.
92. What is the difference between CAD drawing working model space and layout space? Answer: The model space is the space for graphic entities, and the layout space is the space for the layout of drawings.
93. What is polishing? The commonly used polishing method has those? Answer: The action of improving the surface finish of the mold core is called polishing. Commonly used polishing methods include mechanical polishing; chemical polishing; electrolytic polishing; ultrasonic polishing; fluid polishing; magnetic abrasive polishing.
94. What is the function of carrying water? Answer: The function of water transportation is to control the temperature of the mold core.
95. What is a mold? Answer: 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.
96. Mold classification? Answer: 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 the different production processes and products produced. According to 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? Answer: Reverse engineering is the accurate and high-speed scanning of the existing sample or model by a high-speed 3D laser scanner to obtain the 3D contour data, cooperate with the reverse software to reconstruct the curvature, and perform online accuracy analysis of the reconstructed surface , Evaluate the structure effect, and finally generate IGES or STL data, based on which rapid prototyping or Cnc Machining can be performed.
98. What is an exhaust duct? What is the function of the pie tank? Answer: The groove on the broken or scratched surface of the mold core for exhaust is called the exhaust groove. The function of the exhaust groove mainly has two points: one is to remove the air in the mold cavity when the molten material is injected; the other is to remove various gases generated during the heating process of the material.
99. What is called a pouring system? Answer: The plastic flow channel from the nozzle of the injection machine to the cavity is called the pouring system. The gating system includes the main runner, branch runner, gate and cold slug well.

100. Advantages and disadvantages of hot spit.
Answer:  Advantages: 1. No nozzle material, no need for post-processing, making the whole forming process fully automated, saving working time and improving work efficiency. 2. The pressure loss is small. 3. The repeated use of the nozzle material will degrade the performance of the plastic, and the use of the hot runner system without the nozzle material can reduce the loss of raw materials, thereby reducing product costs. 4. The hot nozzle adopts standardized and serialized design, equipped with various nozzle heads to choose from, and has good interchangeability.

Disadvantages: 1. The closing height of the overall mold is increased, and the overall height of the mold is increased due to the addition of hot runner plates. 2. The heat radiation is difficult to control. The biggest problem of the hot runner is the heat loss of the 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. The cost of mold manufacturing has increased, and the price of standard parts of the hot runner system is higher, which affects the popularity of hot runner molds.

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