Many products made in China, and elsewhere in Asia, include components made of plastics that were melted and formed with the use of a mold or a die. And yet, not many buyers are familiar with that material and the related fabrication processes.
This article, written by Renaud Anjoran, founder of Sofeast in Shenzhen, will help you with the design, development, production, and quality control stages. Don’t rely on your suppliers for all the information about your products.
Thermoplastics, or thermosoftening plastics, can be molded at a high temperature and can be recycled relatively easily.
The most common ones in China are acrylic (PMMA), acetal (POM), nylon (PA6.6), polycarbonate (PC), acrylonitrile (ABS), thermoplastic (PET), polypropylene (PP), low-density polyethylene (LDPE), and polyetheretherketone (PEEK), polystyrene (PS).
By contrast, thermoset plastics have an irreversible chemical structure. They offer much higher heat resistance and structural integrity. They are a totally different category and call for different processing.
What are some typical applications for thermoplastics?
Here are some examples:
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Your product will have to withstand a certain environment and will need to have certain visual qualities. Some of the most common criteria to have in mind are the following properties:
It is also possible to mix several of these materials, or in some cases to add glass fibers to improve performance.
Many plastic products made in China are injection molded. To simplify, this process consists of:
Another common process is extrusion. To simplify, this process consists of:
Extrusion is also a very popular process for forming thermoplastics, producing 36% of all plastics consumed worldwide (ranging from films, sheets, rod, pipes coats for electrical wires, window frame profiles, etc.)
Other processes can be used, but they are less common. I’ll focus on injection molding here.
Let’s focus only on injection molding. Sometimes the tooling costs 2,000 USD, and other times it costs 200,000 USD.
Why such a large difference? It depends on the following factors:
a. The complexity of the part, e.g. moving sections, inconvenient angles, different thicknesses…
b. Size of the part – this directly impacts the size of the tool and the amount of steel required
c. Number of cavities in the tool – a single-cavity tool means more cycles are needed to make a certain quantity
d. Degree of automation (automating the unloading frees up operator time, but requires an upfront cost)
e. Metal hardness – from aluminum for a few hundred shots, to H13 steel for millions of shots.
f. Surface finish required
g. Mark-up added by the manufacturer and/or a trading company (tooling is often made by specialized fabricators, and sometimes by the factory that will do the injection)
We wrote about an example (a car dashboard) in this article.
In addition to the cost, making a mold usually takes about a month. And adjustments can make this process longer. Don’t forget to add this into your schedule!
There is a real quality difference between no-brand locally-sourced polymers and branded ones coming from China (e.g. Chimei), Taiwan (e.g. Formosa), Germany (e.g. BASF, Bayer) and the USA (e.g. Dupont, Sabic).
Therefore, in many cases, customers are well advised to do this.
One common reason is for performance and consistency reasons.
Another reason is for safety. Last week I was discussing with a friend who works in a kitchenware factory, and he mentioned that most of the polymers they use come from outside of China. This is quite common for products that need to be in contact with food or beverages.
Either the factory is very well established and can be trusted to handle this, or the importer directs the supplier. If you deal with an average Chinese factory, I’d strongly suggest directing what polymer supplier must be chosen.
If you purchase large volumes, you can push your supplier to share the invoice and the delivery note, to prove they bought the polymer from your source.
Or you can find a wholesaler and work hand in hand with them. (Your supplier is probably also buying from the same type of wholesaler – they seldom have sufficient volumes to buy directly from the raw material producer.)
If you purchase very high volumes, you can make a deal directly with the raw material producer, and they will confirm they delivered a certain quantity to your supplier.
Having said that, if you purchase a few hundred pieces at a low price, persuading a manufacturer to use your source might be very difficult. This is something small buyers can struggle with.
What you really, really don’t want is to have a mold made and then have the manufacturer switch from one polymer to another based on the “deals” they can make with their suppliers, to consume some old excess stock, or for other reasons.
The mold is made and tested for a certain material, and there is little flexibility for production. Switching materials or even brands could impact the dimensions, finish and mechanical properties of your part.
In addition to directing the polymer source, you might also want to specify your tolerance (or lack thereof) when it comes to the content of recycled granules (known as regrind). This can be tested on the molded parts, to a certain extent.
Absolutely. It is not only possible but also quite common.
I guess China is the largest producer of plastic parts. Every major raw material producer has a sales team that deals with Chinese customers and works with local wholesalers.
For example, if you need high-quality nylon P6.6, you can contact Invista’s sales team, or look for one of their authorized resellers. They are an American company. I remember seeing an Invista booth on a trade show in Hong Kong, so they are not hiding.
You can request your supplier to share the invoices and the delivery notes with you.
You can contact the material supplier directly and ask for the best way to confirm their product is used. Helping you do this is in their interest.
Chemical analyses in a laboratory are usually an option, as every brand will have its own specific formula for their polymer and the analysis results should match the technical data sheet provided by the raw material supplier.
In some cases, you can burn the plastic and compare the behavior observed with that of the “real” plastic.
Thailand is a good alternative source. Vietnam could also be an option if you find an export-ready supplier that is not fully booked, which is a challenge in 2019, with Trump’s China tariffs.
If you are ready to pay higher prices, you will find good sources in Taiwan, Korea, and Japan.
First, there are issues due to the use of poor polymer (wrong type of plastic, the excessive proportion of recycled material…) and poor preparation (e.g. insufficient drying might result in cracks).
Second, there are quality issues due to the injection molding process: sink marks, voids, very visible weld lines, very visible flow lines, warping, short shots, burn marks, flash, and so on and so forth. We show some examples in this article.
And third, these parts are often processed further. They might be machined, they are often assembled, etc. Many things could go wrong during this post-processing stage.
If we come in to check a finished product, we work based on the client’s specifications (and we can help put together a checklist document, if needed) and approved sample. Our QC technicians
have an eye out for the common defects I listed above. The objective of thermoplastic quality inspections is to detect and flag quality problems.
If you need to reduce the risks of quality issues, we need to be involved much earlier:
a. Audit of the manufacturing plant, to assess risks for your project and to confirm the maturity of their processes
b. Product design review, to avoid potential issues in manufacturing
c. Tool design review (looking at gate type, ejector pin positions, sliders, and other moving parts…)
d. First-article inspection to confirm the tooling but also the injection press setup – this is mostly dimensional and visual checks
Sofeast is an engineering, quality assurance, and supply chain management firm that helps importers, on the ground in China. Sofeast works mostly for companies that develop their own custom mechanical and/or electronic products. Visit their website for more information.
Plastic materials and products play an important role in almost every aspect of our lives from simple to cutting-edge technologies. From ball point pens to complex components used in the space program; buttons on shirts to bulletproof vests and prosthetic limbs, plastics can be found in a myriad of everyday products.
Plastic injection molding is one of the most basic and reliable methods for manufacturing plastic components. Like 3D printing, it is highly accurate and a staple in manufacturing. Every industries from food to automotive rely on plastic injection molding.
As an extremely competitive market, it is imperative to keep start up costs for tooling to a minimum. High-quality plastic injection molding operations provide a comprehensive end-to-end quality assurance system.
When looking for manufacturers whether in the USA or China for industrial or consumer products, selecting a factory with experience in custom injection molding and state-of-the-art facilities is critical in order to ensure success at every stage of the plastic molding process.
Lowest initial cost is what lures companies to have molds and tools built in China vs. America. Tooling costs in North America are often seven to ten times more than China. Production time for tooling often takes six weeks on average. Therefore, huge savings are found in labor savings. It is vital to work closely with an injection molds manufacturer throughout the entire process. This mitigates risk while maintaining timeline and budget. High-quality molds optimize cycle times, and reduces downtime or maintenance issues quickly paying for itself over the life of the mold.
The quality of Chinese mold makers varies wildly, even between projects. So make sure you are working with someone you trust.
Baysource Global works with mold makers that have consistently proven their quality, and constantly monitor their progress until a quality job is achieved.
Our experienced on-site project managers stay continually involved in client projects communicating daily and weekly with progress reports.
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While Baysource can accommodate varying types of needs related to sourcing in Asia, we generally focus on later-stage businesses who are looking to extend, improve or increase their scope of manufacturing.
If you have a general inquiry feel free to let us know and we will make every effort to respond in a timely manner.
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