Rotational Molding Troubleshooting: 4 Tips to Prevent Defects

Rotational Molding Troubleshooting: 4 Tips to Prevent Defects

Minimize expensive rotomolding defects with these expert insights

By Shell Polymers on May 15, 2020

Rotational molding is a major polyethylene conversion type that is used to make a variety of everyday products such as pipe fittings, large containers, bins, and trash cans amongst other things. Unfortunately, defects are a common challenge during the manufacturing of these goods. To find a solution, it’s typical to hunt for a one-size-fits-all fix and assume it will resolve any problem that appears down the line. In actuality, defects can be the result of a variety of issues, so determining the cause can be a complex and lengthy process.

To help converters improve their operational performance, Shell Polymers experts have provided some of their top tech tips below.

Rotational Molding Troubleshooting

1. Transport Resin Properly

In order to start with a good raw material, you need to be careful when transporting resin from silos. If there are too many 90° elbows, the resin may develop “tails,” “angel hair,” or what some converters call “bird’s nests.” Avoid these annoying wisps of resin by properly controlling the equipment and lines used to move the resin.

2. Monitor Temperature

It is always better to use water and air mist during rotational molding to cool faster. Wait five minutes after the heating cycle ends before starting to spray water during the cooling cycle. This best practice will provide a more uniform temperature throughout the part and help to reduce warping. Be cautious not to add too much water because it may act as an insulator, increasing the cooling time and overall cycle time.

3. Choose the Right Resin

Not all resin options are “one-size-fits-all.” Choose a resin that meets your manufacturing and application’s specific needs and runs efficiently in your equipment to ensure a smooth operation. Resins with a broad processing window are preferable in multi-arm rotational molding. This means that the machines can be operated with different molds without over or undercooking any part.

4. Select the Right Resin with An Effective Additive Package

Additive packages are designed for general operational and application considerations. Not every additive package can or will meet your specific needs. Diligent additive selection is important to maximizing the attributes which are most important to your part and molding conditions.

Choosing the right resin with the appropriate additive package will ensure you can not only achieve the performance that you are looking for but also will enable your equipment to run more efficiently by reducing cycle time while improving warping, sintering, and bubble removal.

At Shell Polymers, our number one goal is to support you and your business. While collaboration might look different right now, the focus of our efforts remains on your continued success. Our team of industry experts is committed to Break the Mold and change how PE providers do business and innovate in ways to help our customers optimize their operations.

Learn from Shell Polymers’ passionate team of experts to experience more profitable rotational molding production that produces high-quality products.

Minimize Cycle Time in Rotomolding Operations

Discover tips to reduce cycle times and increase production.

Get the White Paper