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Afbeelding: Germany 1

Big, bigger, biggest: Large part injection molding with Rompa Group

28 October 2021

When we talk about large injection molding machines and the production of large parts we are actually talking about large tonnage injection molding. Rompa Group operates more than 30 large-ton plastic injection molding machines, ranging from 1,000 to 3,500 tons. The bigger the product, the more little details become even more important. At Rompa Group we offer the right infrastructure, knowledge and innovative machinery. These machines are located at our facilities in Germany, Czech Republic, Mexico and China. But what does large tonnage mean? And why is Rompa Group one of the few manufacturers that operate large injection molding machines? Read more about it in this week’s article!

What do we mean with large tonnage injection molding?

We use extremely high pressure to insert the plastic resin into the cavity of the mold during the process of injection molding. The quantity of tonnage necessary is rated by a clamping force which we calculate in tonnage. It’s the amount of force needed to fixate the two halves of the mold together. The tonnage needed for a certain part is relatively easy to discover: the bigger the part, the more tonnage necessary. In many industries you will find large molded products such as large box containers and pallets. The automotive industry needs products like bumpers and car seats. You will also see these products in our home appliances such as air conditioners and washing machines.

Sometimes we talk about injection pressure and sometimes we talk about clamp tonnage. What is the difference and what is the relationship between these two terms? When we talk about injection pressure, we calculate the PSI, pounds per square inch. This number of PSI is required to inject the melted plastics into the cavity. When the pressure is just right, the products roll out with high quality. When we talk about ‘the clamp’ on an injection molding machine we talk about the two halves of the mold. In simple words, we want to keep these halves together with a lot of force while we inject the plastic resin. So, when the pressure of injection is high, the clamp tonnage must be adequate.  

 

Afbeelding: Britax

A production example

Our production facility in Germany is located next to one of our customers, Britax Römer, in the city of Leipheim. This is one of the production sites of Rompa Group that offers large injection molding manufacturing. The machines operating in this facility have a clamping force ranging from 500 to 1300 tons. One of these large items are the children's car seats we produce for Britax Römer that are called the Dualfix i-Size. Safety is Rompa Group´s top priority and we have been manufacturing products with the correct safety measures for the automotive industry for many years. Would you like to learn more about the cooperation and the production of this particular product? Make sure to read it here!

Material selection

The material selection has a big influence on the necessary clamp tonnage. We see many different grades of plastic resin. These are specified by different features such as physical, chemical and environmental resistance. We select the right material based on the requirements of the finished goods. All the different plastic polymers have their own ideal processing temperature. With the MFI (Melt Flow Index) we can measure the ease of flow of the melted plastic. This gives us a clear indication of the specific pressure we need to apply to produce the ideal finished good as per the design. The higher the MFI, the easier the melted plastic flows through our injection molding machines. This means that less pressure is needed due to the easy flow of melted plastics.

Additional services

We aim to transport the parts as little as possible due to the size of the finished goods, hence we offer several additional in-house services to make the process go smoothly and quickly. Some of the services are:

  • Painting or applying the logo
  • Assembly of the parts
  • We can provide custom packaging
  • Hot stamping and pad printing is an option.

 

Afbeelding: MicrosoftTeams-image (6)

Why choose Rompa Group?

There are only a few plastic injection molding manufacturers in the world who offer to produce large products. Rompa Group is proud to be one of these manufacturers to be offering this service to our clients. Large injection molding machines take up a lot of space and need special equipment to keep running smoothly. Facilities of Rompa Group that operate these big machines have a suitable foundation to place machines weighing over 45.000 kg all together. But also think about the space we need to store large parts when the product is ready to deliver. We were able to specialise ourselves in large product injection molding and we are happy to offer this to our clients.

Rompa Group is home to a wide range of injection molding. Think about thin-walled injection molding, high-precision injection molding, 2k injection molding and much more! Are you interested in viewing some more examples? Or would you like to know more about large product injection molding and what we can offer you? Make sure to contact us for all the details required.