Keeney Improves Regrind Quality Using Wittmann Granulators

Press release submitted on behalf of WITTMANN USA.

With headquarters in Farmington, CT, Keeney Holdings LLC is a leading manufacturer and distributor of tubular drainage products.

Keeney was founded in 1923 and has been a part of the Oatey family companies since 2019.  Oatey Co., based in Cleveland, Ohio, is a leader for the residential and commercial plumbing industries since 1916. They operate a comprehensive manufacturing and distribution network to supply thousands of products for professional builders, contractors, engineers, and do-it-yourself consumers around the world.

Keeney has facilities in four US states as well as Canada and China.  At their plastic injection molding operation in Winchester, New Hampshire, USA, they run several Wittmann EcoPower injection molding machines, sprue pickers, granulators, and temperature control units.

Using Reground Material Inline
When Keeney looked to upgrade some older press-side granulators, they contacted Wittmann USA.  With the increased use of regrind in their molding operations, they were concerned with the overall quality of regrind; they also wanted ease of maintenance.  Materials used include PP, TPE, ABS and PVC.

After an initial meeting, Wittmann USA ran a granulator trial run where they obtained Keeney’s material, did a grinding test with screenless and conventional granulators, and also did a regrind quality analysis.

“We find that by running these types of trials, it gives our customers peace of mind,” said Steve Mussmann, Division Manager-Material Handling & Auxiliaries for Wittmann USA.  “When they can see real-world results before placing the order, they know what they are purchasing is going to work well on their specific application.”

For granulator trials, Wittmann’s quantitative approach is to perform a multi-stages sieve test.  Regrind is passed through a series of sieves with progressively smaller hole sizes. Results are interpreted as follows:

  • Particles that do not pass through the top and largest screen (typically > 8 mm) are considered “longs” and may present material handling problems because of their large size.
  • Particles that are captured by the 6 mm and 3 mm sieves are considered good regrind.
  • Particles that pass through the 3 mm sieve are considered fines.

After completing the trial, the percentage of material that is dust and fines is calculated compared with good quality regrind.

“With the increased push towards recycling and sustainability in our industry, the question has always been and continues to be, can we use regrind to make good finished products?,” said Denis Metral, Wittmann’s International Granulators Sales Manager.  “The answer is usually ‘yes’, but it’s important to prove-out the concept to our customers in advance.”

As a benchmark, said Metral, good quality ground material should be:

  • Similar in pellet size to the virgin material.
  • Fewer fines that melt more uniformly, resulting in fewer rejected parts and reduced costs.
  • Uniform and as free as possible from dust and fines, so that it flows more easily and mixes better with the virgin material and other additives in the molding machine.

Improved Performance
After seeing the Wittmann trials, Keeney purchased 7 new Wittmann G-Max 23 granulators, bringing their total number of Wittmann granulators to 15.  They now are up and running alongside their molding machines, which include three Wittmann EcoPower machines, in their Winchester plant.

“We are very happy with the new Wittmann granulators,” said Steve Duval, Operations Manager at Keeney.  “Not only do they perform well by helping us process better regrind, they also help us keep the facility clean and neat.”

Benefits of using press-side granulators for inline recycling of sprues include:

  • No labor is necessary for handling scrap.
  • No moisture in regrind compared to central grinding.
  • Internal reground materials are free of contaminants and cross-contamination with other materials.
  • Keep the material “in the loop” rather than sending it to a landfill.
  • Closed-loop recycling of sprues gives a second life cycle to internal production waste as a valuable secondary resource.
  • Start-up waste and imperfect products can be reground, and are no longer thrown away.

Close Collaboration to Customize Equipment
Advanced Plastics Machinery Incorporated (APM), the New England Representative of Wittmann USA, has helped Keeney by engineering and producing customized upper feed chutes for the Wittmann granulators.

“The sprues and runners on Keeney’s products are often quite large, and sometimes do not have a consistent drop out of the molding machine,” said Bruce Beckmann of APM.  “

“The customized upper feed chutes we designed provide a much larger landing area to the runners, so that they funnel into the granulator without difficulties and directly down into the cutting chamber.”  Beckmann also noted that this chute fits to each granulator and protects the loading area as a safety guard.

The Keeney Manufacturing Company’s GoGreen Initiative
By implementing responsible cost saving practices including the conservation of energy, recycling material, and reducing its use of virgin pellets, Keeney strives to continually reduce any negative impact on the environment.  These practices lead to less waste and scrap, and also have the benefit of reducing the company’s costs of production.

Keeney also strives to produce “Green” products that conserve natural resources and reduce packaging, allowing its customers to do their part in reducing their carbon footprint.

“Our new Wittmann granulators have contributed nicely to our GoGreen Initiative,”, said Steve Duval, Operations Manager at Keeney.  “They help us achieve our overall goals of recycling and reusing what previously would have been waste or scrap materials.”

With headquarters in Vienna, Austria, WITTMANN is a global company with 7 production facilities, 31 subsidiaries, and 24 agencies in 52 countries.  WITTMANN is the only manufacturer offering plastic processors worldwide a complete range of innovative robot automation and injection molding machine technology, along with auxiliary equipment for material conveying, blending, drying, granulating, heating and cooling, for individual work cells to fully integrated project managed system solutions from one manufacturer. Their worldwide sales and service network provides unmatched local service and support.

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