When a product is born, mold opening is essential, and when we need to find a mold opening factory, we often think that injection molds and plastic molds are a meaning, then understand the difference between plastic molds and injection molds, please read this article Will take you to understand the difference!
Plastic mold, a combined plastic mold for compression molding, extrusion molding, injection molding, blow molding and low foam molding, mainly comprising a combination of a die assembly substrate, a die assembly and a die combination card A concave mold of a deformable cavity, a punch having a variable core composed of a punch combination substrate, a punch assembly, a punch combination card, a cavity cutting assembly, and a side cut composite plate. Coordinated changes in the die, die and auxiliary forming systems. It can process series of plastic parts of different shapes and sizes.
Injection molds are a tool for producing plastic products; they are also tools that give plastic products complete structure and precise dimensions. Injection molding is a processing method used in mass production of complex parts of certain shapes. Specifically, the plastic melted by the heat is injected into the cavity by the high pressure of the injection molding machine, and after cooling and solidifying, the molded article is obtained. The injection mold consists of two parts: a movable mold and a fixed mold. The movable mold is mounted on the moving template of the injection molding machine, and the fixed mold is mounted on the fixed template of the injection molding machine. In the injection molding, the movable mold and the fixed mold close constitute a casting system and a cavity, and when the mold is opened, the movable mold and the fixed mold are separated to take out the plastic product. In order to reduce the heavy mold design and manufacturing workload, most of the injection molds use standard mold bases.
It can be seen from the above that there is still a certain difference between the plastic mold and the injection mold, which also facilitates communication between us and the plastic mold manufacturer to avoid making mistakes.
In fact, many of the construction techniques used in car lights are emerging two-color injection molding in recent years. In fact, the embodiment of this process is to have two different colors when the product is processed. When the product is processed, the procedures involved are still complicated. For many people, this two-color injection molding process is very versatile, and general electronic products are the most commonly used.
Two-color injection molding in mobile phone battery applications
The mobile phone that everyone usually uses, after removing the battery, the exposed plastics are generally of different colors. When processing this product, it is necessary to use special two-color injection molding. Generally, when using this two-color injection molding process, the best finished product may be a color, but if you want to be your favorite color, sometimes there is no way to do a color.
Two-color injection molding has broad prospects
For many people, two-color injection molding has helped him a lot, and it is also a major breakthrough in related industries. I hope that everyone can pay more attention to this process, and in the near future, it will definitely give you even more surprises. In fact, when processing plastic products, the accuracy of the mold is very high. When you use the new two-color injection molding process, you must first perform the first shot, then rotate the mold one hundred and eighty degrees before the second shot.
The new mobile phone uses a two-color injection molding process that is unobtrusive and feels good.
Many of the latest mobile phones that are put on the market basically use this two-color injection molding process. In fact, the first button mobile phone is the most extreme embodiment of this technology. The product produced by this two-color injection molding process can not only achieve the beautiful effect, but also feel better when touched. You must also have a deep understanding. The cost performance of related products is also very high.
Usually, the mold has two parts, an upper mold and a lower mold. The steel plate is placed between the upper and lower molds, and the material is formed under the action of the press. When the press is opened, the workpiece determined by the shape of the mold is obtained or the corresponding waste is removed.
Specific plastic mold processing process:
1. The bottom surface is processed and the processing volume is guaranteed;
2. The benchmark of the casting blank is corrected, and the 2D and 3D surface balance inspection;
4. Before semi-finishing, the alignment of the side datum ensures accuracy;
5, semi-finished 2D, 3D profile, finishing all types of installation work surface (including the limit block mounting surface and contact surface, insert mounting surface and back surface, punch mounting surface, scrap cutter mounting surface and back surface) , spring mounting surface and contact surface, various stroke limit working surface, wedge mounting surface and backrest surface), semi-finishing all kinds of guiding surfaces, guiding holes, leaving the finishing process reference hole and height reference surface, and recording data;
6, inspection and review processing accuracy;
7. The setting operation of the fitter;
8. Before the finishing, the reference hole of the process reference hole is corrected, and the remaining amount of the insert is checked;
9, finishing surface 2D, 3D, side punching surface and hole position, finishing process reference hole and height reference, finishing guide surface and guide hole;
10. Inspection and inspection processing accuracy.
Why is the processing speed of this process goal important in injection molding, because it not only relates to the processing cycle of the part, but also determines the economic cost of processing. We often say that the EDM processing speed refers to the certain mass and volume that the workpiece is etched away in the same unit time under the condition of certain pulse parameters, which can be expressed by volume processing speed or mass processing speed respectively.
Plastic mold mirror polishing
On the same surface roughness of the mold steel, the maximum processing speed of the relative electric pulse at the time of electrode loss is an important target for measuring the function of electric pulse processing and machine tool. In general, the manufacturer gives the maximum processing current and the highest processing speed that can be reached under optimal processing conditions. Therefore, when we practice machining, due to the ever-changing scale and shape of the workpiece, the machining conditions and the chip removal conditions are different from the aspiration conditions. Even in the roughing of the machining center, the machining speed is often much lower than the maximum machining speed of the machine tool. .
Each injection processing pulse discharge will leave a tiny pit on the surface of the workpiece. The size of the pit and the amount of erosion data are approximately proportional to the pulse energy, that is, the larger the pulse energy, the heat transferred to the workpiece. The more you will be, the more information will be erased. In theory, the speed of EDM is proportional to the single pulse energy and discharge frequency, but in practice, the effect of a single pulse is not manifested alone, but the result of multiple pulses together, the pulse power is continuous The process of transferring energy to the machining gap in a pulse condition is much more complicated. The processing speed is a multivariate function related to the pulse discharge timing, the pulse interval, the pulse discharge current, the pulse waveform, the processing target function, the electrode data, the chip removal condition, and the like.
Processing speed is very important in mold injection molding. Because this is a prerequisite for the production of plastic products. If the customer asks for a good quality based on the early delivery, the processing time and speed are the most important.
The quality of plastic molds includes the following aspects:
(1) Product quality: the stability and conformity of the product scale, the smoothness of the surface of the product, the utilization rate of the product information, etc.;
(2) Service life: the number of work cycles or the number of parts produced by the mold under the premise of ensuring the quality of the product;
(3) Application and maintenance of the mold: whether it is the most convenient to use, the demoulding is simple, and the production time is as short as possible;
(4) Repairing the cost, repairing the periodicity, and so on.
The fundamental way to advance mold quality: mold planning is the most important step in the quality of the forward mold. Many factors need to be considered, including the selection of mold materials, the usability and safety of the mold structure, the machinability of mold parts and the mold. The convenience of repairing should be considered as much as possible at the beginning of planning. The manufacturing process of the mold is also an important part of ensuring the quality of the mold. The processing method and processing precision in the mold manufacturing process also affect the service life of the mold. The accuracy of each component directly affects the overall installation of the mold. In addition to the influence of the accuracy of the equipment itself, it is necessary to improve the machining accuracy of the mold parts by improving the machining method of the parts and the skill level of the fitter in the mold grinding process. Surface strengthening of the primary molded part of the mold to advance the surface wear resistance of the mold part, and then better advance the mold quality. The correct use and maintenance of the mold is also a major factor in the quality of the forward mold.
For example, the equipment debugging mode of the mold should be appropriate. In the case of warm flow channels, the power supply wiring should be correct, the cooling water circuit should be satisfactory to the planning requirements, and the parameters of the injection molding machine, die casting machine and press in the production of the mold should be consistent with the planning requirements. and many more. When the mold is used correctly, the mold needs to be maintained in a punctual manner. The guide post, guide sleeve and other parts with relative motion of the mold should be filled with lubricating oil frequently. For the molds such as forging die, plastic die and die-casting die, A lubricant or mold release agent should be applied to the surface of the formed part before each molding.
With the development of society, the quality of molds has been paid more and more attention. With the improvement of planning and manufacturing molds, the realization of new mold skills, mold quality has received more and more attention. Quality is a frequently-changed topic, and quality is moving along with the mold skills.
Modern industry's requirements for injection molded parts not only require high precision, but also have excellent connotation quality. In order to get used to this requirement, it is necessary to develop new technology for injection molds. Now, in the southern coastal areas, the injection molds imported from abroad are being gradually promoted. The new technology has played a big role in improving the quality of injection molded parts. In the past few decades, the domestic plastic mold work has developed rapidly, and the craving and demand for talents has become higher and higher. However, the country still cannot solve this thorny problem and has become the primary obstacle to the development of China's mold work.
It is understood that the mold production areas in the coastal areas have not been recruited to varying degrees. In order to attract talents, many local mold companies even recruit across regions and provinces. Three kinds of talents make up the mold work. “Golden collar” personnel are proficient in mold design software and common sense of mold structure, and have accumulated a lot of practical experience in practice. Such people are very suitable as technical directors or technical supervisors of various enterprises. “Grey collar” refers to the personnel who specially design and process the molds in the post. These people account for 15% of the enterprise mold technology positions. The “blue collar” refers to the technical staff who work as the mold for the specific operation and daily maintenance work in the production position, accounting for 75% of the corporate positions, which is the largest demand now. This has become a primary obstacle in the domestic mold industry. Strengthening the cultivation of professional talents has become an urgent matter for the mold industry.
Following the rapid development of plastic molds, according to the new model of injection mold manufacturing in the information age. The production power of injection mold work has greatly improved, and the impact on the manufacturing industry has a milestone impact. Due to the organic combination of information and manufacturing information related to the manufacturing activities of injection molds, the traditional manufacturing industry has been rapidly developed. This advantage has been greatly demonstrated and reflected in the information age. The modern manufacturing process can be seen as the value-added process of the amount of information contained in raw materials, and the driving of industrial information flow will become the mainstream of the manufacturing industry.
Since injection molding products are widely used in daily life, mold technology has become an important indicator for measuring the manufacturing level of a country's products. In recent years, China's injection molds have developed rapidly in quality and quantity, but compared with foreign advanced technology, the technical level of most enterprises in China still needs to be improved. Now, compared with foreign advanced technology, China's injection mold work has the following problems: the contradiction between supply and demand is difficult to solve in the short term: the domestic market satisfaction rate of injection molds has been lacking 74%, and the satisfaction rate of large, fine and long-life molds is lower.
At present, molds in industrialized countries are accelerating their handling to China, and more and more world acquisitions are taking place. The market demand is strong, and it is difficult to keep up with the production. The situation of oversupply will continue for some time. Unbalanced industry development: Although the products of individual enterprises have reached or approached the world's advanced level, overall, the accuracy, production cycle, and service life of molds are still relatively different from those of foreign countries, and the overall level of industrial development is relatively low. .
What do you need to pay attention to in the production of plastic molds? The first thing to look at is the complexity of the structure of the mold. It takes about a month to open a plastic mold. The time required for a complex mold is more durable. Usually a plastic mold is opened, it is required to do a detailed review. After reviewing the road, the mold can be opened. After a plastic mold is opened, it is required to test the mold. The following injection molding industry experts share with you the following requirements for plastic mold production needs? Below I will list five important keys with us.
1. Cooling in the mold (water passage) is related to factors such as product size, shape, plastic properties, and pressure holding time.
2. The roughness level of the cavity of the mold should reach the “mirror level”, otherwise the product is difficult to demould, and the product needs to be too strong to form product damage when it is ejected. There are standard rules for the roughness of the locating pin, the clamping surface and other parts.
3, the plastic mold should have a satisfactory stiffness, otherwise it will be deformed when the mold is kept under pressure, causing the "flash" to select a reasonable exhaust direction and its amount of control. Otherwise, the plastic is not filled and the product is "lack of material".
4, the needle should be selected reasonably, so that the material can reach each place evenly (the flow path is flat), and there must be a satisfactory storage to ensure that the plastic is replenished in the shortening process. Moreover, the shortening factor of each material is different, and the mold has a reasonable shortening rate.
5. The fixing method of the mold and the injection molding machine should be reasonable, and it must be firm and firm to avoid accidents caused by the displacement of the mold. It is also convenient to disassemble. Also, it is necessary to select a reasonable demoulding method and select a reasonable ejector orientation and quantity to ensure that the product is not damaged during the ejection process.
First, the appearance, scale and cooperation of molded products
1. The appearance of the product does not agree with the shortcomings: lack of material, burnt, white, white line, peak, foaming, white (or cracking, breaking), baking, wrinkles and other shortcomings.
2. Weld marks: Generally, the length of the circular perforated weld line is not more than 5mm, and the length of the shaped perforated weld line is less than 15mm. The strength of the weld line can be tested by functional safety.
3. Shorten: The appearance is obviously not allowed to be shortened, and the obvious is not allowed to shrink slightly (the hand does not feel dents).
4. Generally, the flatness of small products is less than 0.3mm, and the requirements of the device are required to ensure the requirements of the device.
5. The appearance of the place can not be air-grained, material flowers, the product generally can not have bubbles.
6. The geometric shape of the product, the accuracy of the scale should meet the requirements of the officially useful open mold drawing (or 3D file). The product public service should be based on the principle of public service, the axis scale public service is negative public service, and the hole class scale is public service. In the public service, the customer has the required requirements.
7. Product wall thickness: The product wall thickness generally requires uniform wall thickness, and the non-uniform wall thickness should meet the requirements of the drawings. The public service should be -0.1mm according to the mold characteristics.
8. Product cooperation: cooperation between the shell and the bottom shell: the misalignment of the outer surface is less than 0.1mm, there is no shaving phenomenon, and the holes, shafts and surfaces with cooperation requirements should ensure the cooperation interval and application requirements.
Second, the appearance of the mold
1. The nameplate of the mold is in good condition, the characters are clear, and the arrangement is regular.
2. The nameplate should be fixed to the mold base close to the template and the reference angle. The nameplate is fixed and not easy to peel off.
3. The cooling nozzle should be a plastic block nozzle, as required by the customer.
4. The cooling nozzle should not protrude from the outer surface of the mold base
5. The cooling nozzle needs to be processed with countersunk holes. The diameter of the counterbore is 25mm, 30mm, 35mm. The chamfering of the hole and the chamfer should be common.
6. The cooling nozzle should have an entry and exit symbol.
7. The symbolic English characters and numbers should be greater than 5/6, and the orientation should be 10mm below the water nozzle. The handwriting should be clear, beautiful, regular and evenly spaced.
8. Mold parts should not affect the lifting and storage of the mold. There should be exposed cylinders, faucets, pre-reset tissue, etc. under the device, and should have support leg protection.
9. The support leg device is fixed to the formwork by screws through the support legs, and the too long support legs can be fastened to the formwork by the machined externally threaded columns.
10. The size of the die ejector hole should meet the requirements of the specified injection molding machine. Except for the small mold, it cannot be ejected with only one center.
11. The positioning ring should be fixed firmly. The diameter of the ring is generally 100mm and 250mm (depending on the model), and the positioning ring is 10~20mm above the bottom plate. The customer has other requirements.
12. The mold dimensions should match the requirements of the specified injection molding machine.
13. The mold with direction requirements should be marked with arrows on the front or rear template. The arrow should have “UP” next to the arrow. The arrow and text are yellow and the height is 50 mm.
14. The appearance of the formwork should not have pits, rust, remaining rings, water vapor, oil holes, etc., as well as shortcomings that affect the appearance.
15. The mold should be easy to hoist and transport, and the mold parts must not be disassembled during lifting. The lifting ring must not interfere with the water nozzle, oil cylinder and pre-reset rod.
Third, mold data and hardness
1. The mold formwork should be a standard formwork that conforms to the specifications.
2. Mold molding parts and casting system (core, moving mold insert, movable insert, splitter cone, push rod, sprue sleeve) data selection performance is higher than 40Cr.
3. When molding plastics that are corrosive to the mold, the molded parts should be made of corrosion-resistant materials, or the molding surface should adopt anti-corrosion methods.
4. The hardness of the molded parts of the mold should not be lower than 50HRC, or the hardness of the external hardening treatment should be higher than 600HV.
Fourth, ejector, reset, thrust ferrule, take-up
1. It should be smooth, no stuck, and no abnormal movement when it is ejected.
2. The top of the slanted top should be polished, and the inclined top surface is lower than the core surface.
3. The sliding part should be opened with oil groove, and the outer surface should be nitrided. The hardness of the outer surface after treatment is HV700 or above.
4. All rams should have a non-rotation position and each ram should be numbered.
5. The ejection interval is limited by the limit block.
6. The reset spring should be selected with standard parts, and the ends of the spring should not be ground or cut.
7. The slider and the core should have the travel limit. The small slider is limited by the tension spring. When the spring is inconvenient, the wave screw can be used. The cylinder core must have a travel switch.
8. The slider core is generally selected as the oblique guide column, and the viewpoint of the inclined guide column should be 2°~3° smaller than the viewpoint of the slider locking surface. If the stroke of the slider is too long, the cylinder should be extracted.
9. When the end face of the cylinder core forming part is covered, the cylinder should be self-locking.
10. There should be wear plates under the large slider with the width of the slider exceeding 150 mm. The material of the wear plate should be T8A. After heat treatment, the hardness is HRC50~55, and the wear plate is 0.05~0.1 mm higher than the large surface. Open the oil tank.
11. The ejector pin should not be strung up and down.
12. Add barbs to the ejector pin. The direction of the barbs should be kept in common. The barbs are easy to remove from the product.
13. The cooperation gap between the ejector hole and the ejector pin, the length of the sealing section, and the appearance roughness of the ejector hole shall be in accordance with the relevant enterprise specifications.
14. The product should be suitable for the operator to take it off.
15. When the product is ejected, it is easy to follow the oblique top, and the ejector pin should be grooved or etched.
16. The top block fixed on the ejector pin should be firm and firm, and the non-formed part should be processed by 3°~5°, and the lower part should be chamfered.
17. There should be no iron filings in the oil passage hole on the mold base.
18. The end of the return rod is flat and there is no spot welding. There is no gasket at the bottom of the embryo, spot welding.
19. The three-plate mold gate plate slides smoothly, and the gate plate is easy to pull open.
20. The three-plate mold limit rod should be placed on both sides of the mold device direction, or the pull plate should be added outside the mold frame to prevent the limit rod from interfering with the operator.
21. The oil passage should be smooth and the hydraulic ejector reset should be in place.
22. The exhaust port should be opened at the bottom of the guide sleeve.
23. The locating pin device must not have a gap.
5. Cooling and heating system
1. The cooling or heating system should be fully ventilated.
2. The seal should be firm, the system should not leak under the pressure of 0.5MPa, and it is easy to overhaul.
3. The dimensions and shape of the sealing groove opened on the formwork shall conform to the relevant specifications.
4. When the sealing ring is placed, it should be buttered and placed higher than the mold surface.
5. Water and oil flow passage spacers should be selected from materials that are not easily corroded.
6. The front and rear molds should be collected and watered.
7. The diameter of the cooling channel is between 8 and 12 mm.
Sixth, the pouring system
1. The gate setting should not affect the appearance of the product and meet the product installation.
2. The cross-section and length of the runner should be designed reasonably. The process should be shortened as much as possible to ensure the forming quality, and the cross-sectional area should be reduced to shorten the filling and cooling time. The plastics lost in the casting system should be the least.
3. The partial section of the three-plate mold runner on the reverse side of the front template shall be trapezoidal or semi-circular.
4. The three-plate mold has a material break on the gate plate. The diameter of the runner inlet should be less than 3 mm. The ball head has a step of 3 mm deep into the gate plate.
5. The ball pull rod should be firmly fixed, can be pressed under the positioning ring, can be fixed by headless screws, or can be pressed by the pressure plate.
6. The gates and runners shall be machined according to the requirements of the drawings, and shall not be allowed to be processed by hand.
7. The gate gate should be in accordance with the specifications.
8. The front end of the runner should have an extension as a cold pocket.
9. The Z-shaped inverted buckle of the pulling rod should have a slippery transition. 1
0. The splitter on the parting surface should be circular, and the front and rear modes should not be misaligned.
11. The ambush gate on the ejector rod should have no external shortening.
12. The diameter and depth of the cold hole of the transparent product should conform to the design specifications.
13. The material is easy to remove, the appearance of the product has no gate marks, and there is no residual material at the product device.
14. Bent hook ambush gate, the two parts of the block should be nitrided, the appearance hardness reaches HV700.
7. Forming part, parting surface, exhaust groove
1. There should be no defects such as unevenness, pits, rust and other appearances on the front and rear molds.
2. The inserts cooperate with the mold frame, and the rounded corners should have a gap of less than 1mm.
3. The parting surface is kept clean and tidy, and there is no portable grinding wheel to avoid the air, and the sealing part has no depression.
4. The depth of the venting groove should be less than the overflow value of the plastic.
5. Inserts should be placed in place, placed smoothly and securely positioned.
6. Inserts, inserts, etc. should be firmly positioned and fixed, the circular parts have a rotation stop, and the copper pieces and iron pieces are not placed under the inserts.
7. The end face of the ejector pin is shared with the core.
8. There are no disadvantages such as reverse buckle and chamfer in the front and rear mold forming parts.
9. The ribs should be smooth out.
10. Multi-cavity mold products, the left and right parts are symmetrical, should be marked with L or R. If the customer has requirements on the orientation and scale, it should meet the customer's requirements. Generally, it will be added without affecting the appearance and installation. The font size is 1/8. .
11. The mold frame locking surface should be in place and more than 75% of the area will be encountered.
12. The ejector pin should be placed close to the side wall and beside the ribs and bosses, and use a larger ram.
13. For the same piece, the numbers 1, 2, 3, etc. should be noted.
14. Each touch surface, insert surface, and parting surface should be in place.
15. The parting surface sealing part should conform to the design specifications. The medium-sized mold is 10~20mm, the large mold is 30~50mm, and the rest is machined to avoid the air.
16. Skin and sandblasting should reach the customer's requirements evenly.
17. The appearance of the required product, the screws on the product should have a shrink-proof method.
18. The top of the screw column with a depth of more than 20 mm should be used.
19. The wall thickness of the product should be uniform and the error should be controlled below ±0.15mm.
20. The width of the rib should be less than 60% of the wall thickness of the exterior surface.
21. The sloping roof and the insert on the slider should have a firm fixing method.
22. The front die pierces the back die or the back die into the front die, and the bevel should be locked around the machine and machined to avoid the air.
Eight, injection molding production process
1. The mold should have the stability of injection molding and the repeatability of process parameter adjustment within the normal injection molding process conditions.
2. The injection pressure at the time of mold injection is generally less than 85% of the maximum maximum injection pressure of the injection molding machine.
3. The injection speed of the mold injection molding, the injection speed of three quarters of the stroke is not less than 10% of the extra maximum injection speed or exceeds 90% of the extra maximum injection speed.
4. The holding pressure at the time of mold injection is generally less than 85% of the maximum injection pressure.
5. The clamping force of the mold injection molding should be less than 90% of the additional clamping force of the applicable model.
6. In the process of injection molding, the removal of the product and the nozzle material should be simple and safe (the time generally does not exceed 2 seconds).
7. The mold with insert products is convenient for the inserting device when the production is made, and the insert is fixed firmly.
Nine, packaging, shipping
1. The mold cavity should be cleaned and sprayed with anti-rust oil.
2. The sliding parts should be lubricated.
3. The sprue bush inlet is sealed with grease.
4. The mold should be equipped with a locking die, and the specification meets the design requirements.
5. Spare parts for spare parts should be complete with a list and supplier name
6. The import and export of mold water, liquid, gas and electricity shall be sealed by sealing method to prevent foreign matter from entering;
7. The exterior and exterior of the mold are sprayed with paint, and the customer has the required requirements.
8. The mold should be moisture-proof, waterproof, and bump-proof packaging, as required by the customer.
9. Mold product drawings, structural drawings, cooling and heating system drawings, warm runner drawings, spare parts and mold data supplier details, operating instructions, test mode statement, factory inspection certificate, electronic documents should be complete.
This paper analyzes how the plastic product mold reduces defects during processing, mainly from the following five aspects.
1. Reasonably use the cooling lubricant to play the three functions of cooling, washing and lubrication, keep the cooling and lubrication clean, and control the grinding heat within the allowable range to prevent the workpiece from being thermally deformed. Improve the cooling conditions during grinding, such as the use of oil-impregnated grinding wheels or internal cooling wheels. The cutting fluid is introduced into the center of the grinding wheel, and the cutting fluid can directly enter the grinding zone to exert an effective cooling effect to prevent the surface of the workpiece from being burned.
2. The quenching stress after heat treatment is reduced to a minimum, because the quenching stress and the reticulated carbonized structure under the action of the grinding force, the phase change of the structure is extremely easy to cause cracks in the workpiece. For high-precision molds, in order to eliminate the residual stress of grinding, low-temperature aging treatment should be performed after grinding to improve the toughness.
3, eliminate the grinding stress can also be immersed in the 260 ~ 315 ° C salt bath for 1.5min, and then cooled in 30 ° C oil, so the hardness can be reduced by 1HRC, residual stress reduced by 40% ~ 65%.
4. For precision grinding of precision molds with a dimensional tolerance of less than 0.01 mm, attention should be paid to the influence of ambient temperature, and constant temperature grinding is required. It can be seen from the calculation that for a steel piece with a length of 300 mm, the material has a change of about 10.8 μm at a temperature difference of 3 ° C (10.8 = 1.2 × 3 × 3, and the deformation amount per 100 mm is 1.2 μm / ° C), and each finishing process needs to be fully considered. The impact of this factor.
5, using electrolytic grinding processing to improve mold manufacturing accuracy and surface quality. In electrolytic grinding, the grinding wheel scrapes off the oxide film: instead of grinding the metal, the grinding force is small, the grinding heat is small, and no grinding burrs, cracks, burns, etc. occur, and the surface roughness is generally better than Ra0. .16μm; In addition, the wear of the grinding wheel is small, such as grinding cemented carbide, the wear of the silicon carbide grinding wheel is about 400% to 600% of the weight of the hardened carbide. When grinding with electrolytic grinding, the wear of the grinding wheel The amount is only 50% to 100% of the amount of cemented carbide.
Nowadays, the use of extruded plastic molds is also very common. If you do not notice the quality problem at the time of selection, then the later stage will seriously affect the normal use. Today, I will tell you how to judge the quality of plastic molds.
First, we must look at the thickness of this mold when choosing, although the mold does not need to use too much force, or other harsh environment, but due to the phenomenon of mold and demoulding often encountered, the plastic mold will be very Easy, problems such as loss, deformation, etc. The basis for solving these problems is to widen the thickness of the mold. Therefore, in the process of selecting the mold, we can analyze the quality of the mold from the thickness.
Second, look at the specifications of the extrusion die, the good mold can control the size of the extruded plastic products produced in the error of a few millimeters, and the inferior mold often produces a product error of several millimeters or even A few centimeters.
Third, look at the material and workmanship of the entire mold, good mold should be very smooth inside and outside, look shiny, and feels slightly moist, hand inferior mold may have burrs or pits on the surface, the two It is to stand tall.
Mold cleaning is a key process in mold maintenance and maintenance, and it is also a bottleneck restricting mold maintenance. Because the speed of mold manufacturing is much faster than the speed of mold cleaning, and the mold is quickly cleaned, it is ready for the next production, so the time left for mold cleaning is quite limited. How to clean the mold?
1. Standardized cleaning procedure
Systematic mold maintenance is based on maintenance requirements and consistency of maintenance operations. In order to achieve the "cost-effective" goal, cleaning molds must be careful: develop a detailed mold cleaning program. When cleaning different parts of the mold, such as internal cleaning of the press, wiping along the edge, regular cleaning, and main cleaning, the cleaning operation method is also different.
After a certain period of operation of the mold and after visual inspection of plating wear, track marks, and mold residue content in the venting and non-venting areas, the technician can determine the procedure and frequency of mold cleaning by visual inspection. Therefore, it is important to understand the cycle of safe operation of the mold and to document the observations of residue accumulation and wear inside the mold.
Based on the mold having a certain operating cycle, all molds should be accompanied by documentation of the relevant maintenance procedures and maintenance intervals. In general, controlling the internal grease level and gear broaching, sliders, internal shaft pins and bushings, and other moving parts are key to ensuring stable production. Other factors affecting production include contamination or blockage of the waterline and sprinklers, leakage of manifolds, rust and corrosion due to water leakage or condensation.
2. What level of cleaning is enough
Usually, when the molding process is completed, dirt or residue is often left on the mold, and the final cleaning requirements are different for different kinds of residues. Resins such as polyvinyl chloride produce hydrogen chloride gas, which can corrode many types of die steel. Some other residues are separated from the flame retardant and the antioxidant, which can cause corrosion to the steel. There are also some pigment colorants that can rust the steel and the rust is difficult to remove. Even ordinary sealed water, if placed on the surface of an untreated mold for a long time, will also cause damage to the mold.
Therefore, the mold should be cleaned as necessary according to the established production cycle. Each time the mold is removed from the press, it is first necessary to open the mold vents to remove all oxidized dirt and rust from the mold and non-critical areas of the stencil to prevent it from slowly corroding the steel surface and edges. In many cases, even if the cleaning is completed, some uncoated or rust-prone mold surfaces will soon appear rust again. Therefore, even if it takes a long time to brush the unprotected mold, the surface rust cannot be completely avoided.
Many molds now have "self-cleaning" vent lines that have a high gloss. By rinsing and polishing the vents to the degree of polishing of SPI#A3, or by milling or grinding, the residue is discharged to the waste area of the vent line to prevent residue from adhering to the surface of the roughing stand. . However, if the operator uses a coarse brushing pad, emery cloth, sandpaper, grindstone or a brush with nylon bristles, brass or steel to manually grind the mold, it will cause excessive cleaning of the mold.
In general, when the surface of the mold is subjected to high-pressure pulverization cleaning using hard plastics, glass beads, walnut shells, and aluminum pellets as an abrasive, if the abrasive is used too frequently or improperly used, the polishing method also causes The surface of the mold is filled with voids, and it is easy for the residue to adhere to it, resulting in more residue, abrasion, or premature rupture or burrs of the mold, which is more detrimental to the cleaning of the mold.
Therefore, by finding a cleaning device suitable for the mold and the processing process, and referring to the cleaning method and the cleaning cycle recorded in the archive document, the maintenance time can be saved, and at the same time, the wear of the mold can be effectively reduced.
(1) Product quality: the stability and conformity of the product size, the smoothness of the surface of the product, the utilization rate of the product materials, etc.;
(2) Service life: the number of work cycles or the number of parts produced by the mold under the premise of ensuring the quality of the product;
(3) Maintenance and maintenance of the mold: whether it is the most convenient to use, easy to demould, and the production auxiliary time is as short as possible;
(4) Maintenance costs, maintenance periodicity, etc.
The basic way to improve the quality of the mold: the design of the mold is the most important step to improve the quality of the mold. Many factors need to be considered, including the selection of the mold material, the usability and safety of the mold structure, the machinability of the mold parts and the mold. The convenience of maintenance, these should be considered as thoughtfully at the beginning of the design. The manufacturing process of the mold is also an important part of ensuring the quality of the mold. The processing method and processing precision in the mold manufacturing process also affect the service life of the mold. The accuracy of each component directly affects the overall assembly of the mold. In addition to the influence of the accuracy of the equipment itself, it is necessary to improve the machining accuracy of the mold parts by improving the machining method of the parts and improving the technical level of the fitter in the mold grinding process. . Surface strengthening of the main forming parts of the mold to improve the surface wear resistance of the mold parts, thereby improving the quality of the mold. The correct use and maintenance of the mold is also a major factor in improving the quality of the mold.
For example, the installation and debugging mode of the mold should be appropriate. In the case of hot runners, the power supply wiring should be correct, and the cooling water circuit should meet the design requirements. The parameters of the injection molding machine, die casting machine and press in the production of the mold should be consistent with the design requirements. and many more. When the mold is used correctly, the mold needs to be regularly maintained. The guide post, guide sleeve and other parts with relative movement of the mold should be filled with lubricating oil. For each of the forging mold, plastic mold and die-casting mold, A lubricant or mold release agent should be applied to the surface of the molded part before molding.
With the development of society, the quality of molds has received more and more attention. With the enhancement of design and manufacturing molds and the realization of new mold technologies, mold quality has received more and more attention. Quality is a frequently-changed topic, and quality is improving as mold technology improves.