Plastic injection molding

Polypropylene injection molding

Polypropylene injection molding

Polypropylene is one of common plastic resin which used for home appliance and medical plastic parts. It can be used for cup, washbasin, garbage can, basket and toys etc..  It can be also used for disposable medical vessel and box etc, sure you should use medical grade polypropelene. It is cheaper than ABS, PC, PC/ABS and nylon etc. resin. Also it is softer than them.  Polypropylene abbreviation is PP. PP with super folding resistance, so it can be used for lots of folding box such as  stationery and glass box etc. PP is not possible to do the painting process, but it is okay to do the printing.

Polypropylene injection moldingPP raw material is semi-transparent. Also you can pigment to have various semi-transparent color for PP injection molded parts.

To help you to save cost for PP injection molding, below we will talk about how to save cost on the prototype, mold making and injection molding.

Prototype making for Polypropylene

On the PP prototye making, generally it is not possible to carry out the folding performance. There is CNC machining, RTV casting and SLA printing to make PP prototype. You can also choose ABS resin to make the PP prototype.

Save your cost on Polypropylene injection mold

What is injection mold?

Injection mold is a tooling to form the Polypropelene or the other resin plastic product.

Choose right steel for Polypropylene injection mold

As you know PP is not so hard, generally it will use cheap steel such as P20, 2311 or 2312 to make the mold. If the injection mold core and cavity is lower than HRC 44, we call it prehard steel. For PP injection mold, we can use prehard mold. But for high volume injection mold, for example if the mold life is more 1000000shots, you need to consider through hard mold, it means you can choose H13 or 2344 for core and cavity.

If you do not know the quantities you are going to make based on your marketing, you can use prehard mold first.  If you purchase Polypropylene injection molding in China, you can always use prehard mold as mold maker will assure the mold life, anyhow you need to confirm with your mold manufacturer.

Define mold cavity for your injection mold manufacturer

If mold maker ask you how many cavity you need for your mold. It is like to ask you how many same parts you are going to put into your injection mold. This affect the production capacity. Generally the injection molding just take a few seconds to make one shot(cavity).  In case you are not professional, you can let mold maker know how many piece you are going to order each time, then you plastic mold manufacturer will carry out the mold layout.

Plastic injection mold manufacturing

Plastic injection mold manufacturing

Also there is family mold, it is to have different plastic parts in to cavity. If you do so, you need to let your mold factory know if you have different color for each parts, also the useage of each part into the cavity for your final assembly products.

Tips on Polypropylene injection molding

You should choose the right PP injection molding machine. Generally the high speed injection molding machine is more suitable to inject polypropylene. This is thanks to PP resin with high flow performance. This also need mold manufacturer to choose right mold manufacturing process and have reliable design for PP injection mold, otherwise it is easy to have flash. Please kindly noted the common standard injection machine is also suitable for PP injection molding, the difference is on quality and product capacity.

Clean room injection molding plant ChinaMold temperature will be used on the PP product structure. Cold water is widely used for PP injection molding to increase to product capacity.

Tips to purchase Polypropylene injection molding in China.

There are many injection molding factory in China. Some of them is mold manufacture, some of them is injection molding manufacture, also there is trading company. All of them can receive your orders. But if you face mold manufacture, you will have higher mold cost, you need to let them know your injection mold is to leave in the mold factory for production but not to have mold to import to your Country. If it is injection molding manufacturer, generally you can get reasonable mold cost.  But on the different location of China and even if it is different people to quote, there is difference on the mold price and unit price.

To have affordable price, you need to let injection molding manufacturer know below specification for PP plastic molding.

  • How many quantities you need to order each time?
  • Color for each of your parts
  • QTY for each part to assemble one your final product. If you have many parts to inquiry in one time, you have BILL OF MATERIAL form.
  • You need injection mold or you need to do the production in your molding manufacturers’ plant.

Once you have same specificaiton for your mold maker, then they use same specification for quotation, then it is easier to carry out which one with competition.


CNC machinie

China plastic injection molding solution

Plastic injection molding productWe will talk about a few details to have the plastic molded products manufacturing in China. We will have a few guides here to help you to do China plastic injection molding. You will also know the advantage and disadvantage to have the plastic manufacturing in China. Then you can choose to have China plastic injection molding or not have China plastic injection molding.

China plastic injection mold manufacturing

We should talk about the cost for China plastic injection mold making first, the mold cost including the steel cost, mold base, manufacturing cost and labor cost.


China plastic injection mold steelPlastic moulds steel

There are lots of subsidiary company of the worldwide sale plastic mould steel in China such ASSAB, DAIDO and SCHMOLZ+BICKENBACH etc. Normally the mold steel you can bought in North America and Europe, you can also buy in China.

Also China have lots of qualified plastic mould steel supplier such as LKM, Baosteel, HBIS and Fushun Special Steel etc. These steel factories also have long term history and biggest steel factory in China. Normally they have more exhibition to instruct their products, they did not have lots of experience to sale the steels on the web. To be honest the steel factory’s customers is normally not on the web.  So the consumer in North America and Europe did not understand the China mold steel factory.

Normally the China local mold steel is commonly and widely used for very large plastic injection mold manufacturing for automotive mold manufacturing and large consumption goods etc.

You can download mold steel list and review more information on our injection plastic mold steel and plastic injection mold base page.

China plastic injection mold base

Pin point gate injection mold base

China have one of four mold base manufacturer LKM founded on 1975. Most of plastic injection mold importer from Europe and North America should be know this company very well.  In LKM, they offer standard mold base as LKM standard, also they can offer custom standard plastic mold base. But the custom mold base is much more expensive than the LKM standard, this is the reason why there is lots of custom mold standard mold base supplier in China.  More than 30 years developing of modern  mold industry in China, there are lots of qualified China mold base company, China mold steel company and China mold manufacturers as well as professional mold industry practitioners.


Plastic injection mold manufacturing machineCNC machinie

In China there is also easy to import the high technique mold manufacturing machine such CNC, EDM machine and low speed wire cutting machine wordwide machine company. In China including Taibei, there are a lots qualified plastic injection mold manufacturing machine such as TopeEDM , YCM , Victor CNC and Takisawa CNC etc.

In China mainland, there are also lots of CNC machine supplier such as SMTCL CNC and Harvest Star etc.

Plastic injection mold manufacturing labor cost

As China education developing, there are more and more university student join into the plastic injection mold and plastic product manufacturing engineering. There is more worker to compete with the others to get the mold company mold engineering position. The month salary today is reduced 50% compare to the the engineering month salary on 2000. The salaries of the EDM, CNC machine and wire cutting machine operation and technician is also reduced a lot accordingly.

But you heard that China salary is increased every year, why above is not the same. Yes, you are right, the common worker and operator’s salary is increased every year, but this is not the technician to manufacture injection mold.

China plastic injection mold quality

From a few decades development, China mold manufacturing is very full-blown industry in the world, the quality is very competitive. There is also four major mold manufacturing industry location in China. Zhejiang province import and join into the mold manufacturing and plastic product development, but the Guangdong province make the plastic injection mold manufacturing quality much more stable, and make the mold manufacturing with large standard manufacturing  and produced lots mold industry technician.


Plastic injection mold shipping from China to international

Today, the plastic injection mold shipping is most advantage than before. In China and HongKong, there are lots shipping forwarder handle the shipping service for manufacturers. Also your local market also have lots of shipping forwarder coordinate with China shipping forwarder to handle the shipping.

The plastic mold shipping is very convenience for all of manufacturers and importer. You just need to find the forwarder to prepare the goods, the commercial invoice and custom declare and cleaning document, sure you should check the shipping progress with express company or shipping forwarder.

Plastic molds and plastic products shipping solution

China plastic injection mold manufacturing advantage and disadvantage

I think you should have a clue for advantage and disadvantage once reading above China plastic injection mold manufacturing. Anyhow as the internet developing, the plastic injection mold manufacturing and plastic product manufacturing competition is not between China and USA and China and Europe etc. It is global competition, every injection mold factory in the world who have the on-line marketing, then they will be the competitor with you. It is not that you would not like to purchase oversea, it is that you should have your plastic products with competition in the world.  As my point of view, I think all of the Country have the good and competitive mold factory, you just need to choose the mold manufacturers suitable for you.

China mold manufacturing advantage is not just on the plastic injection mold manufacturing factory, is also based on China education, China plastic injection mold manufacturing machine, China culture and China open and reforming development etc. It is like a compositive competition.


China plastic injection molding solution

I think you should be interested if you have China plastic injection molding or not and if there is advantage. We should also consider the cost, lead time, quality, communication and service etc. Then we will talk about this.

China plastic injection molding cost

China plastic manufacturing solutionWe should the plastic injection molding cost including the resin cost, labor cost, injection mold machine cost( unit cost per shot) scrappage and package cost. Then we should calculate the molding cost from these coefficient.

Plastic injection molding resin cost

Different get the plastic resin with different resin cost.

  •  The difference is from different resin cost supplier,
  • Different tax to take and difference VAT to undertake and return(this just affect the plastic molding for the production that you will use more than one ton resin)
  • Use same plastic resin but different brand, you did not specify this.
  • Use different resin to quote but you did not specify this
China plastic raw material manufacturerChina plastic molding solution

There are lots of China plastic raw material supplier such as Chimei, you can use these resin if it will not affect your plastic product quality, these resin can be cheaper than the resin from North America and Europe.

Also there are lots of resin supplier have the production base in China such as SABIC, Polyone and LG etc.  All of these make the plastic resin is similar or cheaper than the resin in North America and Europe.

 China plastic injection molding machineChina plastic injection molding solution

There are also lots of China plastic injection molding machine supplier such as HaiTian, Yizumi and Chenhsong etc. They offer reasonable and high quality plastic injection molding machine. This is also the advantage of China plastic injection molding.


China custom plastic molding supplier

Turnkey solution to control plastic injection molding tolerance

There are lots of people are talking about that how to control the tolerance for plastic molding. I combine my experience with a few exporter who have more than 20 years experience for molding industry. I hope following information will be very useful for you.

What will affect the plastic injection molding tolerance

  • Plastic injection molding resin
  • Mold manufacturing & injection molding project management including engineers, sales & communication etc.
  • Plastic injection mold machining accurate
  • Mold design concept
  • Molding parameter
  • Injection molding machine quality including brand, local or import one
  • Injection molding machine selection including machine size, screw diameter, injection volume and clamping force etc.
  • Quality control including inspection of mold components, electrode and plastic products

First of all we talk about the mold manufacturing & injection molding project management

Lots of people miss to control this on the plastic product tolerance. This is first process we should control the tolerance. We should control from the samples if you are mold factory, if you are mold or plastic product buyer, you should control this on the information offer process.

What we should offer to mold manufacturing factory and molding factory or ask from buyer to control the tolerance?

Plastic product 2D drawing: There should be tolerance label for all of the dimensions. This is target what customer need to reach. If you have surface finishing and secondary process for this products, please offer this information on the 2D drawing. Also please throw away the habit to talk to your mold manufacturing supplier for this kind of requirement on email. If not, you have risky to have your supplier to miss information if the one you are working have no good project management.

Plastic product 3D drawing : Have this drawing to provide to your plastic mold maker, then they check the details of the plastic product on the drawing. Also if your good and professional mold supplier limited on the capability, they will reply you.

I suggest you to read plastic injection mold life on our blog to know more about that the mold life for the tolerance and cost. Normally the accurate mold should be made with through hardness core and cavity. Please offer mold life for mold manufacturer.

Above process is to control the plastic product tolerance during the quotation, this is the communication process, and is the basic process to have tolerance under control.

How SEASKYTOOLING to control the tolerance on the quotation process?

  • Lessons for all of the salesman to understand what we should ask from customer
  • what we should ask based on different customers
  • We clean individual cases up during our service, use this to help you and our salesman
  • We have easy understanding form to collect customer demand to our CRM
  • Professional engineers coordinate with salesman to check and study the information from you
  • Also most of salesman have mold engineer experience

Based on above, we make sure we can get the enough information from you to proceed the quotation and assure you have no risky to miss the tolerance control.

Control the tolerance on different plastic resin

This is one of most important process to control the tolerance.  Different resin on injection molding with different dimension even if it is the same injection mold due to different resin with different shrinkage.

For the POM, PP and PE etc resin, they have big shrinkage, it is more difficult to control tolerance than PC, ABS, Nylon with glass fiber and PC/ABS etc. Normally PC, ABS and ASA etc. plastic resin with shrinkage lower than 6 ‰ is easier to control a few dimensions with +/-0.02 mm, assure it is possible to control to more accurate tolerance for a few dimension. We do not suggest to use the high shrinkage resin to have accurate plastic parts.

Control the tolerance on plastic mold design process

This is one of whole process to check the information provide by customer and manufacture the information on plastic mold design and input on plastic mold factory for mold manufacturing. Your mold supplier should consider following for the mold design and even more than these:

  • Plastic resin shrinkage
  • Plastic product gate location
  • Safe steel for accurate dimensions
  • Use the inserts as possible for the accurate dimensions
  • Use the inserts as possible for the easy breaking feature of mold
  • Consider the suitable injection molding machine
  • Learn the plastic resin specification and input this on the mold design
  • Consider the molding parameter during the mold design
  • Prepare the solution to prevent the deform, short shot, burning etc. common issue during injection molding
  • Mold designer have full check list to check the mold design even if you think you are very  professional
  • Run the mold flow to test the mold design and plastic product design
  • Optimize the mold design and plastic product design

Control the tolerance on plastic mold manufacturing process

  • Choose the right process to manufacture plastic mold components
  • Inspect plastic mold components including the electrodes and mold inserts
  • Assure the plastic mold components is accurate
  • Relieve the stress for the large mold core, cavity or mold plates after manufacturing
  • Measure the plastic mold components and record
  • Inspect plastic products dimensions after injection molding trial and record
  • Measure deviated dimensions on the mold after mold trial. Find the clue to improve the dimensions on the mold
  • Choose the right injection machine according to your injection mold including choose the right screw of injection machine based on the resin and plastic part, clamping force, injection volume, Min-Max mould thickness and ejector stroke etc.
  • Record the molding parameter during mold trial, not only the parameter on the injection machine. You should also record the mold temperature, test the actual temperature of mold and set up temperature of injection machine.

Plastic injection molding tolerance control

If the mold is released for mass production, you should also control the tolerance of the injection molding parts. First of all you have to control the whole dimension, at least you should measure the biggest length,width and height of product. If this have no big change, this means your injection parameter should be correct probably.

Give more importance on the first 100 shots once you start the production. Once the mold running a few hours, the parameter should be not the same, you should check the tolerance, this is the reason why we suggest to check large size and accurate dimensions each hour. Please noted the mold trial is different as the production. Even if you got a good shot on mold trail, it is not the case you can get a good shot on long time production. Please check and record, you will learn lots of information.

Also you should measure the accurate dimension at least per hour to make sure it is correct. You can measure it more frequent based on your production quality control.

You should also check the following things during injection molding

  • Plastic injection molding parts color
  • Plastic injection molding parts surface finishing
  • Plastic injection molding parts small feature including ultrasonic welding line, small bosses, small posts and small ribs etc.
Injection molding polycarbonate project box

Polycarbonate injection molding parts manufacturing solution

Polycarbonate injection molding resin is one of common engineering resin.

Polycarbonate plastic resin applicationPolycarbonate injection molded instrument gauge meter enclosure

Three major application areas of polycarbonate engineering plastics is a glass assembly industry, automobile industry and electronic, electrical industry, followed by industrial machinery parts, CD, packaging, computers and other office equipment, medical and health care, computers and other office equipment, medical and health care, film, leisure and protective equipment etc.

Polycarbonate can be used as the glass doors and windows, polycarbonate laminates are widely used in protective window bank, embassy, detention and public places, for aircraft cockpit, lighting equipment, industrial safety baffle and bulletproof glass.

Polycarbonate plates can be used for all kinds of signs, such as steam pump dial, dashboard, warehouse and outdoor commercial signs, point type sliding indicator.Transparent molding polycarbonate carmer lens

Polycarbonate resin used in car camera system, instrument panel system and interior system such as front cover, reinforced with automobile front plate, the reflective mirror frame, door sets, operating rod sheath and resistance flow plate.

Polycarbonate is used as a junction box, socket, plug and sleeve, gasket, TV conversion device, connecting line bracket lower communication cable, switch box, telephone switchboard, switchboard element, relay case.

Polycarbonate can be used with low load parts, household appliance used for motors, vacuum cleaners, washing machine, Coffee machine, baking bread machine, power tool handle, all kinds of gear, worm gear, shaft sleeve, guide, the refrigerator shelf.

Polycarbonate is the ideal material for optical disk storage medium.Molded polycarbonate gaute merter cover

Polycarbonate  bottle (container)  have very good performance such as transparent, light weight, impact resistance, high temperature resistance and corrosion solution etc.

Polycarbonate and Polycarbonate alloy can be used as a computer frame, shell and auxiliary equipment, printer parts. Modified polycarbonate with high energy radiation sterilization, boiling and baking disinfection can be used for blood sample apparatus, blood oxygenator, surgical operation instrument and kidney dialyzer etc.

Polycarbonate can be used for helmets, protective masks, sunglasses and sports goggles.

PC film is widely used for printing chart, pharmaceutical packaging, film type commutator.

Polycarbonate injection molding process

This is general polycarbonate injection molding process. During your polycarbonate injection molding, you should read your resin specification, your products and mold design from your polycarbonate molding supplier to set up the injection molding parameter. You can always find the the resin specification on

Poly carbonate Drying Before molding PC resins are hygroscopic and pre-drying is important. Recommended drying conditions are 100 – 120 C (212 – 248 F) for 3 to 4 hours. Moisture content must be less than 0.02% prior to processing.
Polycarbonate Molding Melt Temperature 260 – 340 C (500 – 644 F); higher range for low MFR resins and vice-versa
Mold Temperature For Polycarbonate Molding 70 – 120 C (158 – 248 F); higher range for low MFR resins and vice-versa, On the PC molding process, we should prepare hot oil supplies or hot water supplies for injection mold temperature control.
Fill Pressure As high as possible for rapid molding
Injection Speed Slow injection speeds when small or edge gates are used; high speeds for other types of gates

Polycarbonate injection mold manufacturingInjection molding polycarbonate project box

Steel choice for transparent polycarbonate injection mold

You should choose 420 series stainless steel for polycarbonate injection mold. There are lots of kind of 420 series stainless steel. If you need the surface finishing higher than SPI A3, you had better to choose the ASSAB S136 and NAK80. If it is SPI A3, you can choose LKM 420.  You can also see the injection mold steel post on our blog to know more for the mold steel choice.

Steel choice for opaque polycarbonate injection mold

You can choose the mold steel as the normal injection mold. Please be sure that you will not switch to have the transparent plastic molding products from this mold.  Please read more details for the mold steel choice based on mold life on post “plastic injection mold life“.

Plastic injection molding

Plastic injection molding

China plastic molding companySEASKYTOOLING is China plastic injection molding factory working for plastic injection molding and plastic injection mold manufacturing for custom plastic product development of medical device, automotive, medical, telecommunications, electronics, computer, industrial, biomedical, construction and consumer industries etc.

Plastic injection mold manufacturing in China plastic injection molding company SEASKYTOOLING

What kind of plastic injection mold China plastic injection molding factory SEASKYTOOLING make?

Plastic injection molding

SEASKYTOOLING make export mold and domestic mold for medical device, automotive, medical, telecommunications, electronics, computer, industrial, biomedical, construction and consumer industries etc. Most of plastic injection mold is made for automotive, electronics and electric.

Where is China plastic injection molding factory SEASKYTOOLING market?

Our market is in Europe, America, Oceania and Mid-East. To be honest, we can make the plastic injection mold and plastic injection molding production for global market.

China injection molding

What is the advantage for SEASKYTOOLING to make plastic mold and plastic injection molding production?

  • Most of engineers in SEASKYTOOLING have more than 10 years experience for plastic injection mold industry.
  • Free charge of DFM analysis with plastic mold quotation, on this DFM analysis we will find out all of the possible issue on the plastic product design based our experience of mold manufacturing and molding production.
  • Mold flow analysis before the plastic injection mold design, we will find out all of the possible issue of the plastic injection molding and offer suggestion to optimize plastic product design and plastic mold design.
  • Weekly report with picture for plastic injection mold manufacturing, you can understand the mold manufacturing progress each week with picture and time line.
  • Molding report and dimension report
  • No MOQ for plastics injection molding
  • Custom package and bulk package are welcome
  • You can have us for the plastic molding parts shipping or plastic mold shipping, also you can use your old forwarder for the shipping service. We have long term relation ship with FedEx and DHL as well as the sea freight forwarder, we can also have competitive price and lead time information of the shipping for your compare to choose the most valuable shipping solution.

 Plastic injection molding manufacturing in China plastic injection molding factory SEASKYTOOLING

Custom plastic injection molding

  • Various color as per your samples or RAL, or Pantone for plastic molding manufacturing plastic product
  • Specializing in thermoplastic molding with all type of thermoplastic including ABS(with glass fill), Polystyrene, Polypropylene(with glass fill), Polyethylene(with glass fill), Polystyrene, Acrylic,, Acetal, Nylon(with glass fill), PBT(wih glass fill), ASA, PVC, CPVC, UPVC, PC(with glass fill), PC/ABS, PPS, PPA, Elastomers, PPO, POM etc.
  • Surface finishing for plastics injection molding manufacturing parts: Texture(Mold Tech, Yick-Sang etc.), silk-screen printing, painting and plate etc.
  • No MOQ for plastic injection molding production
  • More than 10 years for plastic injection molding production in China for global market
  • Send us China mold supplier SEASKYTOOLING plastic mold inquiry now