Re-grind resin | Cutting-Edge POS Systems Manufacturer | Jarltech
Does re-grind resin diminish the original structural strength of the plastic? This article provides a brief introduction to re-grind resin Jarltech is a Re-grind resin, Why does the surface strength of a plastic product decrease when using re-grind resin? manufacturer. Your comprehensive business solutions: All-in-One Panel PCs, POS system, self-service kiosk, smart card reader, touch monitor, digital signage manufacturer. Jarltech International Inc., established in 1987 in Taiwan, specializes in developing and manufacturing POS and Kiosk systems, notably for restaurants, retail stores, and supermarkets.
Re-grind resin
Why does the surface strength of a plastic product decrease when using re-grind resin?
Does re-grind resin diminish the original structural strength of the plastic? This article provides a brief introduction to re-grind resin
Why does the surface strength of a plastic product decrease when using re-grind resin?
Engineers face a challenge when incorporating recycled resin into plastic parts. The more secondary material that is added, the more the plastic degrades, reducing its original structural strength.
It is also susceptible to the problem of plastic cracking, particularly in stressed areas such as the hook and screw hole positions. Nevertheless, the incorporation of recycled materials into plastics raises environmental concerns.
Why does plastic contain recycled secondary materials that may reduce its strength? This issue is being investigated on two levels
1. Origin of recycled secondary material
Do you believe that a plastic injection molding company should start by incorporating secondary materials? Is it feasible to use raw materials to protect the environment? No, the main reason is cost saving, because secondary materials are more economical.
Do you expect the plastic factory to use the same plastic materials as the original plastic pellets?
Consider this scenario: You specify Sabic (formerly GE) PC materials for the plastic pellets, but will the manufacturers actually receive Sabic's recycled PC materials? Or could they collect any recycled PC material? Worse yet, could they potentially opt for ABS?
The blending of PC materials means that manufacturers cannot incorporate recycled materials, as this would result in a reduction in quality due to the increased presence of inferior plastic particles.
Another factor of uncertainty with recycled materials is storage. Typically, these recycled materials are not stored properly and are often exposed to the elements, including wind, sun and rain, off-site.
You may have seen it: an ordinary plastic chair left out in the sun for an extended period of time begins to fade and eventually becomes brittle. This scenario gives you an idea of how the physical properties of recycled materials can deteriorate, resulting in uncontrollable variations in quality.
2. The variation of MFI values before and after plastic injection
Second, let's assume that your plastic injection process is meticulously carried out, ensuring complete adherence to the material of the original plastic pellets. Alternatively, you can choose to purchase other recyclable materials with similar characteristics from the same brand.
Based on experience, the Melt Flow Index (MFI) of common plastics typically sees an increase of about 20~30% before and after the plastic injection process. If you're not familiar with MFI, it refers to the flowability of the material. This indicates that the structural strength may decrease after the plastic is ejected.
In thermoplastics, the molecular chains are part of the polymer crystals, which intertwine to contribute to a high level of structural strength.
As the plastic is compressed and sheared by the lead screw of the injection molding machine, the long molecular chains are broken, resulting in shorter chains and a reduction in molecular weight. This process is known in engineering as chain scission.
The strength of the entanglement between the molecules weakens, resulting in a decrease in overall strength.As the price and availability of thermoplastic resin continues to fluctuate, it is prudent to maximize the use of available resin. A common way to achieve this is through regrind.
When a project is completed, the excess material and rejected parts can be recovered and reused as regrind. This regrind can either be blended with new resin or used on its own.
What are the key considerations when re-grinding plastics?
When a thermoplastic material is subjected to both thermal and mechanical stress, it undergoes a process known as "heat history," which results in weakening and increased brittleness.
Both the processing heat history and the grinding process itself can degrade the physical, chemical, and flow properties of the thermoplastic resin and any products made from the regrind.
The biggest concern with polymer degradation is often attributed to temperature or heat history. However, if properly handled during processing, many resins can maintain their physical properties for a limited number of regrinds.
What is the optimal ratio of regrind to virgin material to use?
Standard practice in the molding industry is to blend 20 to 25 percent or less regrind with virgin resin. However, it's not uncommon to see a range of 100 percent virgin to 100 percent regrind used in production.
Deviations may occur due to
• Inadequate training of resin handlers.
• Incorrect calibration of either the virgin or regrind feeder and unbalanced mixing of materials.
• Inadequate adherence to shop floor discipline or established procedures.
• Establishing and following proper shop floor procedures and maintaining discipline are critical to preventing potentially disastrous results.
Another important consideration is that while the initial mix may contain 20% regrind, all subsequent passes will always contain some of the previous regrind mix. The resin from the first pass remains in the resin supply.
Check with your resin supplier to determine the number of molding cycles your resin can withstand before properties begin to degrade by more than 10 percent. Also, find out which properties tend to show signs of degradation first.
What are some possible issues to be aware of?
Ensure that resins such as nylon, polycarbonate, polybutylene terephthalate (PBT), and polyethylene terephthalate (PET) are properly dried prior to initial processing.
If not, they can be hydrolyzed in the barrel of the molding machine. This chemical reaction significantly shortens the polymer chain length and leads to degradation. Mixing degraded regrind with virgin material at a level of 25 percent could have a significant impact on the performance and function of subsequent parts.
Temperature control is critical. Processing virgin resin at temperatures higher than recommended is a sure way to accelerate polymer degradation.
Consistent particle size can also be an issue. Without regular maintenance, a grinder can produce a wide range of pellet sizes, from fine, dust-like particles to chunks ¼ inch or larger.
During plasticizing or screw rotation, the screw does not melt these different sized granules at the same rate. This can potentially affect the properties of the finished part.
Repelletizing can address this issue by melt filtering the regrind to remove all non-plastic contaminants. To ensure process stability, it is critical to perform routine grinder maintenance, which includes sharpening blades, cleaning the machine, and checking the screen for proper operation.
What is the biggest challenge you face during the regrinding process?
In our experience, the primary problem is contamination, which includes foreign plastics and other materials. Think about how often production stops due to a clogged hot tip.
One cost-saving approach is to exclusively use virgin resin in hot runner tools, reserving the re-grind for cold runner tools. While this may not be feasible for everyone, when it is, it proves to be a successful strategy.
What are the solutions to these problems?
Consider using 100% regrind instead of mixing it with virgin resin. This eliminates the potential problems mentioned above. With this approach, you utilize all of the virgin resin and introduce 100 percent regrind into the machines.
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Re-grind resin | High-Quality Self-Service Kiosk Solutions | Jarltech
Located in Taiwan since 1987, Jarltech International Inc. has been a developer and manufacturer of POS and Kiosk systems for restaurants, retail stores and supermarkets. Their main software and hardware products include, Re-grind resin, small business POS systems, self-service kiosks, smart card readers, Bluetooth thermal printers, embedded motherboards and all-in-one panel PCs, focusing on providing interactive kiosk solutions.
Leverage Jarltech’s 30+ years of expertise in developing innovative POS and Kiosk systems tailored for diverse business needs in restaurants, retail stores, and supermarkets. Our specialized solutions, encompassing IPC, Touch Monitor, Thermal Printer, and Smart Card Reader, are designed to elevate your business operations, ensuring seamless transactions and enhanced customer experiences.
Jarltech has been offering customers global B2B solutions with Jarltech’s POS and Kiosk Systems since 1987, both with advanced technology and 35 years of experience, Jarltech ensures each customer's demands are met.