Grinding pallet scrap is not for the faint of heart. It’s actually one of the toughest mixes of material to grind in the forest products industry. Keeping this unique challenge in mind, Cresswood Shredding Machinery has developed its EVER-NEW Technology to tackle the demands of pallet scrap grinding along with reducing costs of machine ownership, and operational headaches.
Jack Cress, CEO of Cresswood said, “Reality Check – The pallet industry is a hostile environment for grinding equipment – it’s what we call extreme grinding.”
Jack further explained, “Without a doubt the most challenging applications on the planet for this kind of size reduction and recycling equipment are found in pallet repair, and in pallet manufacturing operations converting scrap material. High-volume pallet repair and recycling facilities can literally reclaim 2 – 3,000 pounds of nails per day from pallets and pallet components processed through our low-RPM, single-shaft grinders. That’s roughly equivalent to the weight of an original Volkswagen beetle.”
Cresswood as a Company
Cresswood Shredding Machinery, a division of Dun-Rite Tool & Machine Company, designs and manufactures the ‘Destroyer’ line of single-shaft, low-RPM wood grinders, and the complete line of Cresswood tooling, at its facility in Cortland, Ill., 60 miles west of Chicago.
Formed in 1978, Cresswood initially designed and built combustion equipment for biomass energy applications. It then shifted its focus to shredder/grinders in order to deliver efficient size reduction of material and the precise particle sizes of wood fiber required for biomass operations.
New Technology for a More Demanding Industry
A major focus of its new initiative is being green in two ways – lighter on the pocket book when it comes to total cost of ownership and environmental impact. Jack said, “The general changes represented by EVER-NEW Technology are one of the biggest leaps in innovation for Cresswood since we’ve been making grinders.”
Jack said, “EVER-NEW Technology is the ‘next level’ result of Cresswood’s commitment to continuous improvement of our grinders. It’s as much about our evolving engineering process, and the precision manufacturing of our single-shaft grinders as about reaching any specific end point. Meeting the needs of our customers will drive future EVER-NEW innovations.”
Cresswood selected the following key drivers for its new technology – increasing durability, designing ‘renewability’ into the machines, and lowering the total cost of operation. This focus begins with keeping grinders ‘tuned-up’ to standard operating parameters, thus increasing energy efficiency, optimizing output quality, and gaining the greatest productivity possible. Jack said, “With EVER-NEW Technology, Cresswood aims to give customers the tools to extract the maximum value from their Destroyer Grinder by eliminating barriers to ‘standard’ operation, extending its usable life, and finding ways to do more with less.”
A key aspect of efficient operation and durability is proper maintenance. According to Jack, EVER-NEW Technology was developed with the maintenance guy in mind.
Mark Anderson, vice president of Engineering at Cresswood, has looked at ‘wear points’ in the field – what’s failing – and examined trade-in machines to determine what maintenance people are spending the most time on. Working with its customers to provide insight, Cresswood has researched and accumulated data on the total life cycle of its grinders.
Jack explained, “Unless you make a grinder easy for customers to maintain, they won’t do it, and that won’t produce a good outcome for anyone. With the innovations and precision manufacturing of EVER-NEW Technology, Cresswood wants to put into the hands of the grinder owner a cost-effective method for maintaining optimal performance, minimizing downtime, and lowering operating costs. That’s the economic bottom-line of this sustainable technology.”
One benefit of EVER-NEW Technology is that the primary wear components on a grinder that require rebuilding can now be easily replaced during routine maintenance for relatively little cost. Cresswood has these parts and components in stock, to eliminate sourcing & shipping delays. This extends the longevity of the units and reduces the future need for entirely new equipment.
Jack said, “Its one thing to be able to rebuild a machine, but to design a machine to be rebuilt is a whole different task. In the single-shaft grinder arena, pretty much all of the competitor’s machines can be rebuilt, but there are a limited number of people who can accomplish it, so the costs are higher.”
To achieve these results Cresswood did more than just design new machinery. It took everything back to the drawing board, including changing its manufacturing process. Cresswood is utilizing precision manufacturing techniques to machine parts, and maintain tight dimensional tolerances. Part of this initiative has been a reevaluation of the materials that Cresswood selects.
Jack said, “Cresswood is building grinders that stay ‘true’ to their standard operating parameters, and that’s efficient, sustainable technology.” .
Jack elaborated, “In single-shaft grinders, rams are cycling and pushing material through the cutting rotors hundreds of thousands of times per year. In order to achieve ‘well-tuned’ performance and durability of a grinder, all of the component parts of the machine have to be precise.”
More than just a novel concept, EVER-NEW has been proven in the field by a number of pallet companies that know the rigors of grinding pallet scrap. Read about two such installations in the accompanying case studies.
For more information about EVER-NEW, contact Cresswood at 800-962-7302 or email info@cresswood.com or visit the Website at www.cresswood.com that includes videos of the EVER-NEW Technology.
Key Features of EVER-NEW Technology
• Replaceable Anvil Support Plates
• Replaceable T1 Bed Plate
• Replaceable T1 Grooved Floor
• Forged, Alloyed, Heat-Treated Drive Shaft
• Expanded Surface Area for Bearing Plates
• Extended Wear Life with Bolt on Replaceable Ram Seals, Bearing Plates, & Guide
Cresswood Drives Quality Fiber Production at Tree Brand
Anyone can grind pallet scrap. But it takes a special focus on quality to produce consistency when it comes to wood fiber. That’s been a big key to the success of Tree Brand Packaging in Denver, N.C.
Chris Helms, president of Tree Brand, said, “The fact that we produce a high-quality post-industrial clean fuel from our scrap is very advantageous with biomass customers. This will be an even bigger market in the future.”
Biomass market development beckons with Tree Brand adding three new customers for boiler fuel. One customer consumes six trailer loads per week. Chris said, “Our grinding operations have really paid off for Tree Brand – we can consistently move the material, and have always found markets to balance any seasonality.”
Tree Brand operates a main plant and headquarters in Denver, N.C. with a second facility located 20 miles west of Chattanooga, Tenn. Its main focus is custom pallets, skids and crates for niche industrial markets, serving primarily the steel, telecommunications, plastics, packaging machinery, and weapons industries.
Even in a down economy, Tree Brand has found a way to stay busy. Chris said, “There’s a fair amount of bad quality out there, and Tree Brand is committed to delivering more than good quality. We have built up relationships with 5-7 mills, and having a solid reputation in a tight-supply environment has given us some advantage where wood availability is concerned.”
Tree Brand produces about 200 -225 tons of wood fiber per month. After running one unit for more than twelve years, Tree Brand traded it in for a second Destroyer, and worked with Cresswood as a pilot partner on its EVER-NEW Technology development.
Jack Cress, CEO of Cresswood Shredding Machinery, said, “Working with Chris Helms and Jeff Hooper of Tree Brand Packaging as key partners, Cresswood analyzed grinder ‘wear points’, designed in ‘part replaceability’, and engineered solutions for jams/bridging of material due to the extreme demands of pallet applications. Tree Brand is a custom manufacturer of heavy-duty pallets, skids, and crates for industrial applications, and the scrap blocks, end trims & slats from hardwood cants are a tough diet -day in, day out.”
Jack further explained, “Within the pallet market, Tree Brand’s requirements were a perfect catalyst for our ‘sustainable design & built-for-renewal’ manufacturing initiative – Cresswood ‘EVER-NEW’ Technology.”
Tree Brand Packaging took delivery in December 2009 of its second Cresswood HF-60-75 Grinder complete with EVER-NEW Technology innovations, which has significantly improved grinder operation at Tree Brand.
Jack Cress visited Tree Brand in 2009 to analyze the company’s specific needs. Chris said, “We were looking to eliminate all chronic maintenance hassles, and Cresswood wanted to engineer in solutions for the long-term – it was a win-win proposition,”
Cresswood tackled three unique challenges for Tree Brand. The first challenge was to minimize damage from tramp metal involvement. Jeff Hooper, maintenance manager for Tree Brand, explained, “Even though we have metal detection & removal on the infeed conveyors from our two saws, and patrol our scrap hoppers, stuff will get through.”
Jeff said, “On the first grinder, the anvils were bedded into the machined area of the floor, and tramp metal would knock the tool holders off, bending them over the tooling. This would cause what’s called a ‘crash’, requiring costly downtime, tooling replacement, and refurbishment of machine.”
Cresswood designed unique tooling anvil/counter knife supports that provide a ‘sacrificial plate’ which will take the brunt of a tramp metal involvement, and protect the integrity of the anvil itself. These new anvil support plates can be easily replaced, at minimal cost, when they are damaged.
The results were a major improvement. Jeff said, “We’ve had some tramp metal events, but haven’t had damage to the tooling, and have quickly brought the machine back to ‘new condition’ which is what we were looking for.”
A second challenge involved slats, thin reject material from its cut-up lines that often have pointed ends, which would get wedged under the grinder ram, jam it, and back up the infeed conveyors.
Cresswood engineered a new ram design which effectively prevents ‘ram jam’, changes the ram position and creates a smaller profile on the hold-downs. Cresswood also engineered a grooved floor for the grinder to further eliminate material jamming.
Jeff said, “Our new Cresswood grinder has never jammed, and the slats are processed efficiently; these innovations have worked.”
The final challenge resulted from grinding blocks; end trims from cants that may be up to 10” in length, a task that single-shaft grinders are uniquely effective at performing. At Tree Brand, these blocks were bridging, preventing the flow of material to the cutterhead. In its first grinder, these long blocks could also jam-up the ram if they were ‘on end’ when fed through the hopper.
Mark Anderson, vice president of engineering for Cresswood Shredding Machinery, said, “Cresswood increased the height of the ram in the new design to eliminate this issue, and the smaller profile on the hold-downs created fewer areas for blocks to bridge. We adapted machine design to effectively process this ‘oversized’ material.”
These solutions fixed the bridging problem, allowing Tree Brand to cost-efficiently convert all the random scrap from its operations into product for its chip markets.
Chris said, “The Cresswood grinder works as good as we could possibly want. They responded to our specific needs, and when something works – you stay with it. As a supplier, they’re at the top of our list.”
M&M Woodworking Turns to Cresswood for Specialized Grinding
Founded in 1973, M&M Woodworking in Kingsport, Tenn. has aggressively developed high-value markets for scrap material from its wood pallet component and manufacturing operations, including ‘cull boards’, and ‘end trims’ from hardwood cants.
“It’s a very specialized product with exact particle size, content, and moisture requirements,” said Nathan Morrell, vice president and co-owner of M&M Woodworking. “The material is used as a component in an engineered product. We have cultivated this market over 7-8 years, and we’ve fine-tuned our fiber product to fit – it’s an on-going process,” he continued, “and we have strong customer relationships.”
As a secondary market, M&M Woodworking provides boiler fuel for a paper company. Biomass energy shows promise as a strong market for its wood fiber. M &M Woodworking accumulates material from three or four locations in its facility and delivers it to the stationary grinding system.
Nathan said, “Because we run a two-stage system, with the Cresswood primary grinder equipped with a one-inch screen, and the secondary hammermill equipped with a half-inch screen, our volume output totals are comparatively low.” Due to this screen combo and customer specs, M &M Woodworking consistently produces 2.5 – 3 tons per hour of finished material which translates to 24 – 25 tons ground in one eight hour shift per day.
M & M Woodworking uses a two-stage grinding system. It processes scrap blocks, cant ends, & culled boards from the pallet manufacturing process. Most of it is green hardwood scrap (primarily poplar and oak). See Chart 1 for a complete breakdown of this system.
M & M Woodworking, Inc. took delivery of its Cresswood HF-7860-75 Grinder, complete with EVER-NEW Technology innovations, in July 2010.
Brad Boulware of Boulware Equipment, a Cresswood sales representative for the southeastern United States, played a key role in engineering, installing, fine-tuning, and trouble-shooting the system with M & M personnel and Cresswood’s field support staff.
M & M had been seriously researching a new grinding system for about four years when the Morrells attended the Richmond Show last May where they discussed their challenges with Cresswood. They had the following criteria for a new grinder:
• Capability to produce a certain Volume Tonnage of Uniform Output
• Cost-Efficient Low-Horsepower Machinery
• Space Efficient System
• Ability to Tie Into an Existing Cyclone System
• Ease of Maintenance & Low Cost of Ownership
• Elimination of Chronic Grinder ‘Weak Points’ & Downtime
Cresswood faced three challenges with the M & M Woodworking system. First, grinding cant cut-offs and other pallet material is the most ‘violent process’ in its pallet operation. Nathan explained, “The anvils or counter knives in grinders take a real beating, and when they get damaged by tramp metal – which will get through, no matter what – you’ve got a very costly crash on your hands. We needed to avoid the extreme consequences of these incidents.”
Cresswood designed a replaceable
anvil support plate made out of mild
steel as part of its EVER-NEW Technology. It will help to absorb the shock and damage in a tramp metal involvement. By having anvil support plates that are easily replaceable, M&M is able to save both time and money returning the grinder back to ‘as new’ standards.
Nathan said the result was that the innovative anvil support plate feature works great and was a key selling feature for its needs.
Another problem on other brands of grinders that M & M previously owned was that the gearboxes were not durable. When they would fail, it would bust bearings, and require a very costly replacement. Nathan said, “It was one of those major ‘problem areas’ that we quite frankly couldn’t afford on the new grinder.”
Cresswood responded by beefing up its gearboxes. It now utilizes a fabricated steel plate gearbox on all its grinder models to assure tramp metal protection for the single most expensive component on the machine. Jack said, “Most grinders, as M&M experienced, utilize cast-iron gearboxes, which can’t take an impact, and will crack.”
The result is a stronger, heavier duty machine than many competitors that is built tough in the right places. Plus, Cresswood offers a ‘Risk-Shield’ Warranty Package, which includes a 3-year warranty on the gearbox, and a limited lifetime warranty on the cutter shaft.
The final challenge that M &M encountered was poor wear life on cutters in previous grinders. These were often difficult and time-consuming to remove from the rotor. Also, the long pipeline for tooling made them difficult for M & M to purchase.
Cresswood’s solution is precision-machined parts from tool steel that goes through a proprietary hardening process to deliver superior tool life value.
Nathan said, “With the upgrade to the Cresswood tooling, we haven’t had to change the teeth yet after almost six months of use…Cresswood has been in business long enough to fine-tune their engineering, and to make all the components ‘mesh’ into a very impressive machine – they’re at the top of their game.”
Chart 1
M&M Woodworking Grinding System
STEP (1) – Cresswood HF-7860-75 Primary Grinder to process/convert wood scrap to nominal one inch particle size; Hopper-fed, ‘dump & go’ infeed
STEP (2) – Cresswood metered discharge, including cross-belt metal
separation
STEP (3) – Cresswood ‘rough-top’ discharge inclined belt conveyor, ‘covered’ to deliver 1 inch product to 2nd stage Hammermill, or direct to truck loading
STEP (4) – Optional trailer loading direct for 1 inch nominal product, or 2nd stage processing through high inertia mill for a higher $$$ value ¼” – ½” minus ‘fluffy’ fiber product
All electrical controls are interlocked to fully integrate the two stages, while requiring the least amount of total horsepower
