A Brief History of POM Plastic Injection Molding
POM (polyoxymethylene) was first commercialized in the early 1950s by DuPont under the trade name Delrin. Its unique combination of properties quickly made it a popular choice for engineering applications.
What is POM?
Polyoxymethylene is a direct polymer with no side chain, high viscosity and high crystallinity. POM fabric, also called acetal plastic, is a semi crystalline thermoplastic with tall mechanical quality and inflexibility. It has exceptionally great sliding properties, great wear resistance and moo dampness assimilation. It regularly alluded to as Delrin or Celcon, is a high-performance building thermoplastic known for its uncommon mechanical properties and flexibility. It’s interesting combination of solidness, quality, and dimensional soundness makes it a favored fabric for a wide extend of applications over different businesses.
It is a flexible fabric that can be handled utilizing different procedures, counting Injection molding, expulsion, machining, and thermoforming. Among these, Injection molding is the most common strategy for creating POM parts due to its productivity and capacity to make complex shapes with exact resistances.
This article will dig more profound into the prepare of POM plastic Injection molding, investigating its focal points, applications, and contemplations.
Types of POM Plastic Injection Molding
Type | Characteristics | Applications |
Homopolymer POM (POM-H) | High crystallinity, excellent mechanical properties, may be susceptible to stress cracking | Gears, pulleys, bushings |
Copolymer POM (POM-C) | Improved impact resistance and stress crack resistance | Automotive parts, consumer goods |
Reinforced POM | Enhanced mechanical properties, such as strength, stiffness, and heat resistance | Structural components, automotive parts, industrial machinery |
Flame-Retardant POM | Improved fire resistance | Electrical connectors, building materials |
Food-Grade POM | Meets food safety standards | Food processing equipment, containers, packaging materials |
Medical-Grade POM | Meets biocompatibility and sterilization requirements | Surgical instruments, prosthetics, medical components |
Conductive POM | Improved electrical conductivity | Electrical connectors, EMI shielding, electronic components |
Low-Friction POM | Very low coefficient of friction | Bearings, bushings, moving parts |
High-Temperature POM | Can withstand higher temperatures | Automotive under-the-hood components |
Color-Pigmented POM | Imparts color or opacity | Consumer goods, automotive trim |
Chemical Structure and Properties:
- POM is a crystalline polymer composed of rehashing formaldehyde units. This chemical structure gives a few alluring properties:
High Quality and Firmness: POM shows amazing ductile and flexural quality, making it appropriate for applications requiring strong mechanical execution.
Dimensional Steadiness: POM has moo dimensional float and fabulous crawl resistance, guaranteeing exact resistances and long-term unwavering quality.
Fatigue Resistance: The material’s weakness quality is tall, permitting it to withstand rehashed loads without disappointment.
Chemical Resistance: POM is safe to an assortment of chemicals, counting aliphatic hydrocarbons, alcohols, and numerous solvents.
Low Coefficient of Grinding: POM has an actually moo coefficient of contact, making it a great choice for moving parts and orientation.
Good Wear Resistance: Its scraped area resistance is tall, guaranteeing long benefit life in applications subject to wear and tear.
Excellent Machinability: POM is simple to machine, permitting for complex shapes and exact resiliencies.
What is the process situation for Acetal injection molding?
- The moisture absorption of POM is low, generally 0.20%-0.25%, usually without drying can be injection molded, but the wet raw materials must be dried. Drain can also improve the gloss and mechanical strength of the product.
- The melting temperature range of POM is very narrow, and the melting and solidification speed is fast, and the crystallization speed is also fast. When the material temperature is slightly below the melting warmth, crystallization will occur and the fluidity will drop rapidly.
- 3. POM is very heat sensitive and not difficult to decompose. The decomposition temperature is 240°C. However, it also decomposes when it is left at 200°C for more than 30 mm. When decomposing, it will give off irritating and abrasive gas.
- POM has high crystallinity. When the amorphous melt becomes a limpid solid, the shrinkage rate is close to 20%. Therefore, pressure filling must be performed to prevent excessive shrinkage to ensure the dimensions of the plastic injection molded part.
- 5. POM has a low coefficient of friction and high flexibility. When the side grooves of plastic parts are shallow, they can be demolded without damaging the plastic role.
- The nozzle diameter of POM should be larger and a straight through nozzle should be used. In order to prevent the flow of mouth water, the beak hole can be flared.
- POM injection molding products are very hard and rigid, and the plastic parts have good demold ability and are easy to demold quickly.
- The resistance of the pouring system to the molten material are small, so the inlet should be increased appropriately, and dead-end stagnation in the flow channel should be avoided as much as possible.
- POM should be molded by screw injection molding machine, the excess material should not be too much, and the residence time in the barrel should not be too long.
- In the case of high material temperature of POM and low warmth of the nozzle, high pressure air injection can easily cause explosion and injury.
- The fluidity of POM melt is medium. The change of flowability is not sensitive to temperature, but more delicate to the change of injection molding pressure.
- For POM injection molding products with metal inserts, the inserts must be preheated at a preheating temperature of 10 0 ~ 150 ℃, which can reduce the internal stress around the place in the plastic parts to keep away from cracking.
- The ratio of shear stress to shear rate of POM melt is almost constant, i.e. Newtonian melt. Melt viscosity is largely influenced by the shear rate, but not the temperature.
- Copper is the catalyst of POM degradation, and the parts in contact with POM should stay away from using copper and its alloy materials.
- In the same POM product, molding shrinkage is not uniform, the thick wall part is cooled slower than the thin wall part, resulting in density difference, making the molten material in the thick wall part flow to the thin part. Therefore, the wall thickness of the product should be as uniform as possible.
- At higher temperatures, POM will decompose into formaldehyde and even formic acid, which can easily wear down the mold, so the mold should be made of corrosion-resistant materials.
Advantages and Disadvantages of POM:
Advantages:
- Excellent mechanical properties
- Dimensional stability
- Chemical resistance
- Good wear resistance
- Low coefficient of friction
- Easy to process
Disadvantages:
- May be susceptible to stress cracking
- Relatively high value compared to some other thermoplastics
- Limited heat resistance
Disclaimer:
The data given in this reaction is for common information and enlightening purposes as it were. It is not aiming as a substitute for proficient counsel or administrations. Continuously counsel with a qualified proficient for personalized direction.
I am not capable for any mistakes or exclusions in the data given. The substance is based on my understanding and translation of the information I have been prepared on.
Conclusion:
POM is a high-performance designing thermoplastic that offers an interesting combination of properties, making it an important fabric in a wide extend of businesses. Its flexibility, unwavering quality, and ease of preparing have cemented its position as a favored choice for requesting applications. As inquire about and advancement proceed to progress, POM is likely to play an indeed more critical part in forming the future of materials science and building.
Future Patterns in POM:
As innovation propels, investigate and advancement endeavors proceed to center on making strides the properties and execution of POM. A few ranges of investigation incorporate: Enhanced affect resistance: Creating modern grades of POM with made strides sturdiness and affect quality.
Improved warm resistance: Expanding the temperature capabilities of POM to grow its application extend.
Reinforced POM: Joining strengthening specialists such as glass filaments or mineral fillers to improve mechanical properties.
Recyclability: Investigating strategies for reusing and reusing POM to decrease natural affect.
FAQS:
1. What is the commonplace shot measure for POM injection molding?
The shot measure can shift broadly depending on the portion estimate and complexity. In any case, it’s for the most part measured in grams or cubic centimeters.
2. How does POM compare to other thermoplastics in terms of its combustibility?
POM is for the most part considered to have direct combustibility. It can be self-extinguishing beneath certain conditions but may require extra fire retardants for particular applications.
3. What are a few common quality control measures for POM injection molding?
Dimensional assessment: Checking parts against indicated resilience utilizing measuring rebellious.
Visual review: Looking at parts for absconds like streak, sink marks, or voids.
Mechanical testing: Assessing properties like malleable quality, flexural quality, and affect resistance.
Chemical testing: Analyzing the fabric composition to guarantee it meets determinations.
4. Can POM be utilized for food-contact applications?
Yes, POM is by and large considered secure for food-contact applications. In any case, it’s fundamental to guarantee that the particular review of POM utilized and the fabricating prepare comply with significant nourishment security controls.
5. What components impact the cycle time for POM Injection molding?
Part estimate and complexity: Bigger and more complex parts for the most part require longer cycle times.
Mold plan: Effective shape plan, counting cooling channels and venting, can diminish cycle times.
Machine settings: Components like Injection weight, temperature, and clamping drive can influence cycle time.
Material thickness: Higher density materials may require longer cooling times.
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