Injection molding still key method in plastic parts manufacturing

Plastic parts companies in mainland China also have facilities for extrusion and are considering using 3D printing but for prototypes and small orders initially.

Plastic parts production in mainland China continues to be based primarily on injection molding, followed by extrusion, while 3D technology has yet to be adopted on a mass scale. The last will be used in prototyping, initial runs, low-volume orders or to accommodate requests.

The first method has the advantages of better precision and higher output, outweighing the concomitant steep cost of making molds. As such, injection-molded parts account for 60 to 80 percent of local output, a share that will likely increase as a number of suppliers invest further in improving in-house facilities.

Shenzhen Kim Dai Precision Mfg Co. Ltd sets aside more than $1 million every year for the development of molds. Xiamen Evergreen Technology Co. Ltd spends $50,000 annually to make its own molds.

For other plastic parts makers, however, outsourcing mold making is still a common practice because this helps lower production cost.

In general, manufacturers highlight installed machinery to demonstrate capability to handle any requirement for this customization-driven line.

Hongkong Yana Technology Co. Ltd has 20 injection-molding equipment, which can churn out 100,000 pieces daily. It turns out 20 sets of molds every year.

Shenzhen Kim Dai boasts an annual production capacity for 1,200 sets of molds, and has 132 injection-molding machines.

YongChangXing International (HK) Co. Ltd owns 110 machines with 60 to 550 tonnage from Toyo and Demag of Japan. For making molds, it has high-speed CNC and AgieCharmilles NC precision EDM equipment respectively from Mikron and GF of Switzerland, and high-speed CNC machines from Japan. The last can process 110 sets every month, each of which yields between 2,000 and 3,000 tons of plastic parts annually.

Besides 10 injection-molding machines, Xiamen Evergreen has five extrusion equipment. It produces 30 sets of molds, which can handle 10 tons of plastic parts a year.

For QC, mainland companies adopt coordinate measuring machines imported from Mitutoyo of Japan, Zeiss of Germany or LK of the UK.

Makers are able to meet mold tolerance of up to 0.001mm, while the typical range for finished parts is ±0.01 to ±0.05mm.

Exports are projected to remain on the rise in coming months. Interviewed companies said their current production capacity levels can meet this.

Outbound volume at Hongkong Yana is anticipated to climb by 50 percent, fueled mainly by demand in the electronics, and electrical and industrial equipment sectors. In 2017, it was 30 percent.

For Shenzhen Kim Dai, the rate of increase will stay at 60 percent, thanks to robust requirement in the medical, optics, automotive, consumer electronics and security fields. Xiamen Evergreen Technology Co. Ltd and YongChangXing looks to another 10 percent growth as orders for plastic parts used in electronics products and the automotive industry rise.

Mainland suppliers export their output mainly to the US, Canada, Germany, the UK, Italy, Mexico, Russia and Austria. They plan to explore prospects in other destinations, including the Middle East and South America.

Plastic parts represent between 40 and 90 percent of overseas shipments overseas. Local enterprises offer CNC-machined, die-cast and stamped parts as well.

Plastic parts makers in the mainland are spread over several provinces. The major hubs are in the cities of Shenzhen and Dongguan in Guangdong province, Wenzhou in Zhejiang, Xiamen in Fujian, Suzhou in Jiangsu and Luoyang in Henan. There are also suppliers in Jiangxi and Shandong provinces.

Types of plastic used

Domestic manufacturers of plastic parts adopt PP, PC, ABS, PVC, nylon, PU, POM and PMMA, while others also combine materials such as PC and ABS, and PC and glass fiber.

Parts for electronics products conform to RoHS requirements.

Most companies source inputs from the domestic supply, although requests for imported variants are accepted. For the latter, they rely mainly on US and Taiwan providers.

The cost of locally available ABS was $2,540 per ton in May, rising 2 percent from the previous six months, while that of PC climbed by about 50 percent.

If this trend continues, makers, already beset by higher labor outlay, will be forced to increase prices in the months ahead.

The products in this gallery have been handpicked by our mainland China-based market analyst for representing current trends in plastic parts from mainland China makers.

Push latch made of nylon 66, POM

This latch for toolboxes and door cabinets from Ganzhou Heying Universal Parts Co. Ltd, model Push Latch DL-2, is made of nylon 66 and POM, and its metal part of SUS. It is priced at $0.24. The 1,000-set minimum order is delivered in 3 or 4 days.

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Plastic part for in-line pumps

Hongkong Yana Technology Co. Ltd’s HKYN-605 model is a clear acrylic part used in in-line pumps. It is CNC-machined and polished. Dimensions are 8x12x7cm and weight is 60g. Price is $8.

The 500-piece minimum order requirement is delivered within 10 days.

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Housings for USB flash drives

Shenzhen Kim Dai Precision Mfg Co. Ltd offers USB flash drive housings such as this Sandisk USB Housing model in ABS, glass-filled PC, POM and PMMA variants and different colors. Such products measure 30x10mm and weigh 5g. The maker requires a minimum order of 10,000 pieces for similar items. Delivery lead time is 15 days.

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Nylon 66, TPE part

From Xiamen Evergreen Technology Co. Ltd, this model EG-155 plastic part is based on nylon 66 and TPE. The 75x22x30mm unit weighs 30g and comes in black. It is quoted at $0.25. Delivery of a 3,000-piece minimum order takes 21 days.

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Plastic part for electronic control boxes

For electronic control boxes, Xiamen Xintonglian Plastic Co. Ltd’s XTL-1110 model comes in ABS, PC, PP and nylon versions. Price is $3.10. The minimum order is 3,000 pieces. Delivery takes 10 days.

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ABS projector shell

This projector shell from YongChangXing International (HK) Co. Ltd, Injection Molding Parts model, uses ABS and oil spray surface treatment. It is priced at $1. The maker has no minimum order requirement and delivers within 28 days.

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