Category Archives: Uncategorized

Notes on Adhesion Improvement between PE and PA in Multilayer Rotational Molding

Before sharing this study on improving adhesion in our member newsletters, we asked Technical Director Nick Henwood to let us know whether the paper would be valuable to rotomolders. He offered some notes for context:

I think this is work is useful, especially in relation to rotomolded gas tanks.

Gasoline permeates PE too easily to pass current conformance tests (EPA and CARB requirements).

PA-Polyamide (aka “nylon”) has much better permeability characteristics, but is also much more expensive than PE.

Therefore it makes sense in principle to make a two-layer moulding using PE with an internal “lining” of PA.

Problem is that inner layer of PA will not adhere to PE and delamination occurs to a considerable extent. Often the delamination is complete.

Anything that improves the adhesion of the two layers would be very helpful.

The first option put forward, plasma treatment of PE powder, is known already, primarily as a way of improving adhesion of PE with polyurethane (PU) foam. Interesting to see it being used for PA.

The second option mentioned, creating polymer “entanglements” has been put forward in principle previously, but actual performance data takes this option forward considerably.

Listing of Resin Properties Update

The ARM Education Committee plans to refresh the  ARM Listing of Resin Properties this spring. ARM supplier members are invited to contribute their resin data to the publication by March 2, 2021. Review the current document here.

Data is provided by suppliers, but test methods and specimen preparation protocols are standardized, to provide apples-to-apples comparison.

Use these forms to enter your data:

When you complete the form, a copy of your submission will be emailed to you. Complete the form for as many resins as you would like to list. If you need to change the data you entered, complete the form again and contact staff to let us the know the date and time of the form that should be deleted.

If you wish to list any specialty materials (e.g. foams, flame retardants, conductives, rotolining, etc.), please contact ARM Technical Director Nick Henwood as soon as possible.

As in the past, suppliers must ensure, with the exception of the melt index, density and ESCR, that all of the technical data in the listing has been obtained solely from rotationally molded specimens and that the data for each resin, with the exception of the low temperature impact data, have been obtained from only one sample per resin. ESCR has been obtained from compression-molded specimens molded under the conditions specified in those procedures. The current version of the ARM Low Temperature Impact test method is version 4.0 (July 2003), available here.

Supplier Members of the Association of Rotational Molders may publish their data in the Resin Properties Listing at no charge; this is a Member Benefit.  Suppliers who are members of other associations affiliated to ARMO (the Alliance of Rotomoulding Organisations) may publish their data for a fee of $1,000 payable prior to publication.  Alternatively, you can join ARM.

Ask Dr. Nick

Dr. Nick Henwood

Technical Director Nick Henwood’s Ask Dr. Nick series allows ARM a way to share his feedback on interesting technical questions we receive at ARM. Here’s a handy list of the ten posts we’ve published so far.

If these articles are helpful, access Dr. Henwood’s many more technical articles written for ARM in the last four years in the complete archive of his blog posts.

Online Education: More than 100 videos and webinars on demand for members

ARM webinars were viewed 10,000 times in 2020, twice as many times as 2019.  This number includes live webinar attendance and recorded webinar views, in which members watch our 10+ years of webinars at their convenience on the ARM website.

We now offer more than 100 videos on-demand for members. Non-members can join ARM here. Members can access all of the titles listed below immediately. 

Continue reading

President’s Message: Annual Meeting Feedback and SWOT Analysis

Here’s an update to our little chart to memorializing 2020:

ARM President, Rick Carlsen

Virtual Fall Meeting

I am happy to report that ARM’s first virtual meeting is successfully behind us.  As with any untested method, there’s a certain level of anxiety that comes with the territory, and this was no different.  While the Forums and Programs committee put together another excellent slate of presentations, the unknown of the unknown weighed heavily on our minds.  Would people participate when balancing the meeting with their daily duties?  Would the technology work as intended?

The results from the meeting show that 98% of attendees reported that the meeting met or exceeded their expectations.  Generally speaking, the technology worked, the presentations were on target and members felt their time was spent in a beneficial way.  We also heard that this format exposed more individuals to ARM than previous meetings since meeting attendance did not require travel expenses.  This is all great feedback that will be taken into consideration for future meetings. 

Another result of moving our meeting online was that our virtual exhibit hall remains open at There you can learn about more than 50 exhibitors and watch dozens of new videos from our suppliers, sharing the newest machines, materials, and more.

While this format worked, we also understand that it is difficult, if not impossible to replace face-to-face meetings.  Although our next planned face-to-face meeting is Rotoplas 2021, it remains a key objective to host a live meeting once it can be done safely and responsibly.

North American Rotomolding Industry SWOT Analysis

ARM conducted a SWOT analysis of the rotomolding industry for our online Annual Meeting. The goal was to get a baseline for the rotomolding process that rotomolders can use as they implement Industry 4.0 technology. This way we can compare where rotomolding is today with where the rest of the manufacturing world is going. 

We sent a freeform text survey asking for feedback. Many of our supplier members also work within other industries with manufacturers who use different plastic processes. Their critical feedback compares rotational molding with other processes.


The strengths are in the eye of the beholder. Short runs, low cost tools, and creative parts, are seen as the strengths of rotomolding but the folks on the shop floor don’t necessarily love them.

Survey respondents noted the flexibility of the process, the shapes we can make, the ability for us to change colors, and the ease of tooling are all strengths.  Many respondents also mentioned low cost tools, which is definitely true in comparison to other plastic processes, and short runs

Durable parts are hugely important. There is a lot of talk about plastic being bad.  The fact that our products are reusable, can be repurposed, and are durable goods, puts us in a different category than other plastics processes.

Other strengths include low capital needs for entry, and our capability of making very large parts. Some of our members are making incredibly large fluid holding tanks. 

So what do our non-molder members say about us? They’re talking not as much about the process itself as they are the industry. Non-members commented on strengths such as the closeness of the industry, networking, and that it is the most cooperative industry to work in. We are unique in that rotomolders are very open and honest with each other. I think that really stems from the entrepreneurial feel that the industry still has. We are a lot of small, agile companies run by passionate business owners. 

In the recent Plastics News, where they list the top rotomolders from 2019, the top 20 molders make up about 50% of the market. The other 400 molders in North America make up the remaining 50% or about $3,500,000 of revenue per business. The entrepreneurial spirit also breeds creativity and fosters sharing. 

This industry feels a lot like craft beer, the other business that I’m involved with. One of the similarities is market reach. Because rotomolded products are large hollow parts they are difficult to ship very long distances, just like craft beer. That may be one thing that’s playing into this cooperative industry. 


One of the most common weaknesses mentioned is that we have a slow process with a higher cost. This really hits home. A number of years ago, a friend who used rotomolding as a very small part of their business summed up rotomolding as “cheap tools, expensive parts.” 

There are material limitations. We do have fewer materials to run than other plastics processes. While there are other materials available, as an industry we choose to run primarily linear polyethylenes. 

Labor is one of the Achilles heels of the industry. We have a very manually driven process that requires almost a craftsman, more than a button pusher, to run our presses and perform secondary operations. Attracting labor, finding people who will work hard, and the general availability of labor, are all becoming more of an issue as we compete against people who are frankly automating their business and making the work easier. 

Our non-molder members talked about resistance to change, not embracing new resins, and focus on material cost rather than value. From talking to other molders and suppliers, and from being around the industry, I think this is accurate. There is a certain stubbornness associated with entrepreneurs and some molders out there are resisting change.

This can be seen when you’re looking at materials and automation. There are more materials out there than linear polyethylene. However, based on cost and other factors, some people choose not to use them. There are also a lot of people choosing not to use automation so I think there’s some pretty fair criticisms or ideas of what the weaknesses are within the industry. 


Within a SWOT analysis, your strengths and your weaknesses are both internal looking. The opportunities and threats are viewed on a macro level. Some of the opportunities our members mentioned are conversions, automation, new materials, and customer market awareness.

Conversions from metal, concrete, and wood are always discussed as we look for the next big product that is a takeaway from another industry. It gets us thinking creatively: what is the product and how are we going to make it?

When we look at some of the weaknesses and threats, automation resolves many of those issues. As an industry, it’s a real opportunity for us to understand how we will make the most of automation. 

At our 2019 Annual Meeting, Toter shared a video of one of their automated machines, where there were 30 – 40 molds on a single machine. Both the molding and trimming operations were being run by a single operator. They accomplished this by leveraging automation. 

It’s interesting that our members labeled new materials as an opportunity because one of our weaknesses was material limitations. Our suppliers are telling us there are more materials that we are resistant to use. Determining what types of materials the market needs, and how to bring those to market will be very important in the future.

Only a few respondents mentioned consumer market awareness but it is a very interesting point. Our non-molder members commented that we need to educate the OEMs and designers on what we sell and the durability of our parts. I think these comments speak to expanding market awareness. 

Kayaks and coolers are the more popular consumer-facing markets for rotomolding. The premium cooler has done a really good job of promoting the process. Many manufacturers tout the process capability of rotational molding in making an almost indestructible product as why our process is superior to other processes. For an opportunity, how do we leverage that? We now have a group of consumers in the market who understand what rotational molding is and, more importantly, they understand the benefit that it has to create a robust product that they love using. We need to leverage that consumer awareness in the future.

Though it wasn’t mentioned in our survey, I think our relatively small market size, coupled with the ingenuity and creativity of some of our entrepreneurs, could really lead to additional opportunities.


While there are a lot of external threats that are plaguing rotational molding, we are going to focus on those specific to our process. Obviously we’re not going to mention things like pandemics because what are the odds of that actually happening?

Lower cost and competitive processes were some of the most frequent results. We know there are other plastic processes out there that are becoming more competitive through automation. We’re seeing blow molders who can make larger and more intricate parts. The speed at which 3D printing is coming into the market and expanding is staggering. We’re also seeing competition with injection molding. 

The next biggest threat that was mentioned was labor availability and skill. As discussed, we are a very manual process and makes it difficult to find people to do the work that we need. When you do hire people, do they have the skills to be able to perform the work? How many rotomolders are hiring people who have never run a drill before? How many people don’t know the difference between certain tools? 

The last threat is environmental. For our industry, people always think of plastics being bad for the environment. You’re not seeing playground equipment and large stock tanks and things of that nature floating in the Pacific. We may not be a part of “Plastic Islands” but we do have microplastics. We do have our resins and our pellets that are washing out of our dumpsters and into the water stream.

There’s absolutely an environmental impact we can have but when we talk about threats, one of the biggest environmental impacts we’re going to have is this emergence of electric engines versus combustion engines. We’re seeing more cars going electric. We’re seeing more components on machinery go from hydraulic to electric. There will probably always be a place for the combustion engine, but as electric motors become more powerful, as battery storage becomes less of an issue, I see this being a real threat to rotational molders, especially considering gasoline tanks, diesel tanks, diesel emission, fluid tanks, hydraulic reservoirs, overflow tanks. That’s a big part of our businesses.

Our non-molder members had interesting feedback about threats to our industry related to rotomolders’ views on tolerances. One of the other really interesting comments made was by a supplier who talked about corporations and holding companies continuing to purchase rotational molding companies, and that the organizations are becoming less entrepreneurial and more corporate. The question or the opportunity we have with that is how do we keep larger corporations engaged? How do we keep larger companies coming to meetings and sharing information, and how can we do that in a way that doesn’t pose a threat to our members? 

What’s Next?

I hope you’ll think about the feedback we received on the SWOT survey. What do you agree or disagree with? From your company standpoint, how do you compete? How do you match up against some of the stereotypes of rotomolding that came up? As you take a look at your internal direction for your business, what should you be doing more of, what should you be doing less of? What do you need to do to change the industry? How do you keep growing your businesses in terms of cost, quality, delivery, and ease of doing business?

It’s pretty clear what other industries are doing and I think there’s some legitimate opportunities and threats within our businesses that we need to take very seriously. 

In conclusion, I think there’s a lot of great things going on within the market. I think there’s a lot of room to improve. I think there’s a lot of opportunity on the horizon and it’s going to be very interesting in the upcoming years to see how people respond. 

Rick Carlsen
ARM President

Long-term properties of roto materials: Should I worry?

Dr. Nick Henwood

ARM recently held its Annual Meeting as a virtual event and this new format seemed to be a great success.  Obviously, we all missed the normal human contact; the chance to meet contacts, former colleagues and friends, in person.  However, as a way of presenting information and opening up discussion, the on-line format certainly seemed to work.

As part of the main event, we organized a technical session with presentations around a common theme, which was “Long-term Properties of Rotomolding Materials.”  There was an introductory keynote, followed by four groups of expert speakers, plus a Q&A session.

I would encourage any of you who missed out on this session to revisit it via the ARM website, where we now have recordings of all parts of the session.  Some aspects of the same subject were also recently covered during our Design Webinar Series (Module 5), which is also available in recorded format.

Does Long-term Properties seem a subject which is rather esoteric and strictly for the “techies” amongst us?  Possibly, but it really shouldn’t!  There are several good reasons why any rotomolder should be aware of the basics of this subject, if not all the detail.

Continue reading

The State of ARM 2020

The presentation above opened our 2020 Annual Meeting which is being conducted online the week of September 21-25. We address what new benefits ARM provided in the first nine months of the year, including 65 new videos in our online member’s library. We highlight some of our longstanding benefits, provide an update on membership, and discuss what’s to come.

Michael Paloian receives the Charles D. Frederick Distinguished Service Award

ARM’s Distinguished Service Award is typically a surprise for the recipient at our Annual Meeting. In that spirit, we interrupted Michael Paloian of Integrated Design Systems as he was about to present the finale of his webinar series on Rotational Molding Design, to announce that he was selected by ARM’s Executive Committee to receive the award.

For more than 15 years, Michael has presented his design seminar to attendees at our Annual Meeting, providing new case studies every time to keep it fresh. For more than 20 years he has acted as an ambassador for rotational molding to the design community.

This year he developed a new program for ARM members, a series of six webinars on design, which we have presented throughout the summer. These have been among our highest attended webinars, attendees rank them as very valuable, and they have led different constinuents in our organization to become active.

Michael Paloian is president of Integrated Design Systems, Inc. (IDS), located in Oyster Bay, New York. Since its inception more than 35 years ago, IDS has developed hundreds of products ranging from MRI machines to pool chlorinators under the direction of Mr. Paloian. Michael’s education as an industrial designer and plastics engineer has provided him with a unique set of design skills, enabling him to design products from concept to production. Mr. Paloian has an in-depth knowledge of designing parts in numerous processes and materials, including plastics, metals and composites. This broad knowledge base combined with his extensive experience in designing hundreds of products provides him with a distinctive advantage in optimizing designs based on materials, process and cost. Mr. Paloian holds more than 45 patents and has served as chairman for a few divisions within the SPE. He has lectured hundreds of times for organizations such as the SPE, SPI, ARM and IDSA. Michael has also written numerous articles concerning design for publications such as Machine design, Design News, Innovation, Rotation and Plastics Design Forum. Mr. Paloian has also lectured in Paris, Rome, Brazil and India.

The Charles D. Frederick Distinguished Service award is presented each year to ARM committee members or other volunteers who go above and beyond the call of duty in ARM activities and committee work.

A designer’s questions on rotomolding properties

Recently ARM presented Class 5 of its Design Webinar Series, which was focused on material properties, as they relate to product design.  The webinar consisted of an initial presentation by ARM’s Technical Director Dr Nick Henwood, followed by a series of questions from Michael Paloian of Integrated Design Systems, the regular presenter of the Design Series.

As a highly experienced designer, Michael’s questions were extremely searching and got into some interesting and relevant detail, so we thought that it would be useful to fully reproduce the conversation between him and Nick below.

For those who missed the live event, a recording of Nick’s complete presentation is now available in the Members’ Area of the ARM website along with Michael’s entire series on rotational molding design.

Continue reading

President’s Message: Understanding the State of the Rotomolding Industry

ARM President Rick Carlsen

Rather than regurgitating past information, I decided to put together a little chart to memorialize 2020:

Rotoplas 2020 is now Rotoplas 2021.  Same great location, same low price.

ARM made the decision to postpone Rotoplas 2020.  There’s too much uncertainty surrounding COVID-19 to continue with the initial plan.  Corporate and governmental travel restrictions coupled with the threat of a Fall resurgence all played into the decision.  The event has been rescheduled for the week of September 20, 2021 in Chicago, IL.

Virtual Fall Meeting

In place of Rotoplas 2020, ARM is hosting an online meeting September 21 – 25, 2020. The schedule is filling up quickly with lots of technical and shop floor rotomolding content. We are excited to bring the education you have come to expect from our in-person meetings to this online format this year. Sign up for the meeting here.

We will host videos for all exhibitors on the 2020 Online Meeting website. These videos will be published on our site the week of August 24 and meeting attendees can click to learn more about the companies and their products. During the Online Annual Meeting (the week of September 21), exhibitors will take part in private Zoom meetings with rotomolders/attendees. ARM staff will schedule and organize all of these meetings across 3 – 5 afternoons that week.

There is no charge for members attending the meeting. We know the current climate makes doing business difficult and as an association, we want to do everything we can to make your investment in ARM valuable. 

Industry SWOT Analysis

An emerging theme of recent meetings and presentations is Industry 4.0; the industrial revolution that leverages cyber-physical systems and the IoT to alert and direct activities based on real-time process information.  To better understand how our industry can keep pace during this latest revolution, we thought it was important to understand the state of the current industry.

To understand where rotomolding fits compared to general manufacturing, ARM is conducting a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis of the industry.  A SWOT focuses on both internal factors, strengths and weaknesses, and well as external factors, opportunities and threats, to highlight the current state.  Based on ARM’s breadth of membership, it can rely on molders, suppliers, and other experts to offer their insights regarding how the industry stacks up against other plastics processors and the general manufacturing industry.

If you have not seen it yet, here is the SWOT survey.  I encourage you to spend 5-15 minutes to participate in this effort and complete the survey.  The responses will be analyzed and shared during the 2020 Virtual Fall Meeting.

Our lives are all being impacted by the events happening around us.  If you would have told me that Tiger King would be the most normal phenomenon of 2020, I would have laughed at you.  Now, I’d rather marry Carole Baskin than jump on an airplane.  There will be a time that we can meet face to face and get back to normal.  Until then, take care of yourself.