Rough mill operations watch their waste.
Depending on who you talk to and which specie is involved, the price increase of lumber can vary from a few percentage points to downright skyrocketing figures. The days of abundant supplies of low-priced, low-defect hardwood lumber may be coming to an end, prompting wood product manufacturers and machinery engineers to look for solutions which can increase yields in their rough mill, the first machining operation in many woodworking facilities.
"I don't see lumber prices falling in the future," said Dan Forrest, sales project manager with GreCon Inc. "The wood-working industry will be looking toward machinery manufacturers to produce rough mill equipment that can improve yields."
Ripping operations in the rough mill are changing to meet this demand. These ripping systems can now be a high-tech operation that integrates laser light guides and computer scanning systems to replace or minimize the human factor in determining maximum yield per board.
"Relying on a computer for maximum yields can be a benefit," said Tom Edmunson, technical sales staff member with Mid-Oregon Industries Inc. "If the program makes good, consistent decisions during the shift to cut out defects, it will help increase productivity and increase yields."
According to industry experts, the three most common ripping approaches utilized in the woodworking industry today are cross-cut/straight line ripping, gang ripping with fixed blades, and selective ripping with movable blades on a common arbor. Each system has unique characteristics in regard to affordability, yield potential and productivity levels.
Crosscut/straight line ripping
Still popular with the furniture and cabinet door industries, one of the first systems to be used to remove defects in the rough mill was the crosscut/straight line ripping operation.
"Straight line ripping is an affordable, easy-to-operate system that offers a straight glue line cut that is necessary for panel lay up," said Bob Jennings, general manager with Mattison Woodworking Machinery Co. "These systems appeal to smaller shops because of their affordability and the ability to run 60 to 180 feet per minute feed speeds."
In recent years, one area coming under scrutiny has been the questionable yield percentages that crosscutting boards first creates. Critics say that crosscutting creates excess waste and recommend straight line ripping first and then eliminating defects with crosscutting.
"lt's a matter of what you're looking for," said Jennings. "Some shops rip first and crosscut later. Others crosscut then rip. What is the application? Do you want wide boards or long boards? These are some of the questions that need to be answered," he said.
Gang ripping involves feeding boards into the saw where the blades are mounted on a fixed arbor, meaning the blades are unable to slide back and forth to cut different board widths. If different board widths are desired, the machine must be shut down so that blades can be readjusted to the desired widths.
"Gang ripping doesn't have the ability to isolate defects as well as select ripping, but more so than cross cutting first/straight line ripping," said Edmunson. "The result is higher average yields over cross cut first/straight line ripping systems."
Gang ripping allows increased productivity because the gang ripping uses multiple blades on a single pass, instead of the single blade used in a straight line rip saw. In addition, gang ripping often can cut the most wood with parallel edges per shift because the blades do not have to reposition themselves before sawing each board. This makes the system attractive for long production runs.
One of the more recent additions to rough mill ripping is the selective ripping, or ripping with movable blades on a common arbor, process. The system processes each board individually, where the ripping decision is based on defect location. The arbor arrangement changes with each board, increasing or decreasing the distance between the multiple blades of the selective rip saw.
"Depending on the customer's application, their system can have anywhere from one to six moving blades on their select rip machine," said Marvin West, vice president of sales with Mereen-Johnson Machine Co. "For example, a furniture manufacturer may have fewer moving blades to give them the required cuts they need. A moulding manufacturer may choose more moving blades to give them the desired net rip considering length, width and knot positioning."
Other benefits of select ripping systems include very high yields, because decisions are often made with computer assistance. Purchase of an additional scanning system or similar computer optimization program is advised with a select ripping system.
"When a board is scanned on a select ripping system, the computer tells the blades where to position themselves for best optimization," said Forrest. "This allows the user to utilize the entire board."
Because of the increased expense of purchasing a select ripping system, taking a close look at its application is important before deciding if it is the correct system, said Edmunson.
"The general rule I use in questioning customers interested in a select ripping system comes in three parts," said Edmunson. "First, will the yield increase offer substantial payback? Second, is your operation cutting five to eight different rip sizes? And finally, are you cutting 10,000 board feet in a shift? If so, perhaps your operation should take a look at a selective ripping operation."
Choosing the right system
So which system is the best for your shop? Many different elements must be taken into consideration before a decision can be reached.
"You need to look at three areas," said John Foster. sales manager with Newman Machine Co. "You need to obtain higher yields and productivity. But beware, because there will likely be a tradeoff between the two. Finally, the system has to deliver the material tolerances you are looking for. If your new rough mill equipment doesn't give good product quality, such as good glue lines, it can lead to failure further down the line."
St. Cloud, Minn. - based Woodcraft Industries utilizes gang rip and selective rip systems to perform rough mill tasks.The company uses a gang rip saw to cut lower grade lumber because it is 10 percent more productive than the select rip system. The select rip system is used to cut more expensive premium and #1 common grade lumber because it offers a two percent higher yield than the gang rip operation, which adds up to substantial savings.
By taking a good, hard look at a company's rough mill requirements and consulting with rough mill machinery manufacturers, it is possible to increase yield and productivity with the correct ripping operation. By paying attention to such elements as product mix, size of shop and number of board feet cut per shift, the correct ripping equipment can be tailored to meet a company's rough mill ripping demands.
The following is a review of some rough mill equipment available to the woodworking industry. For more information, circle the corresponding numbers on the Reader's Service Card. For a more comprehensive overview of rough mill equipment market, consult the 1994 Red Book Annual Buyer's Specification Guide.
The 431-DC straight line multiple rip saw from Mereen-Johnson is a 31-in. capacity saw which allows for additional rip combinations further increasing the customer's lumber yields. The saw is equipped with a 75-hp arbor motor and 5-in. air loaded press rolls.
The MR model 36 dip chain gang rip saw from Tyler Machinery is a heavy-duty, precision, chain feed machine which may be used for straightline, glue joint or general millwork production. The machine features a 36-in.-wide saw arbor and feed chain which can help the user attain yield improvement. Features include cast iron link chain design and six pneumatically loaded material hold-down rolls. The machine may be used with 12-, 14-, or 16-in. diameter saw blades. Maximum material thickness with a 16-in. blade is 4 1/2 in.
The Pinheiro model 300 straight line rip/gang rip from Auburn Machinery Inc. is designed to handle everything from glue line ripping to producing pallet boards from rough hardwood cants. The heavy cast iron AMA has a double V feed chain for precise feeding, an electric lubrication system to protect the feed chain, a usable arbor capacity of 12-, 4 1/2-and 5 1/2 in. thickness capabilities and other features.
The PR2000 is the largest rip saw from Mid-Oregon Industries and has up to six independently adjustable blades. This selective ripping reduces waste by isolating the defects into one rip width. This produces a higher percentage of long, wide clears, more valuable cut stock and a reported 15 to 20% increase in yield.
The Servo Sleeve mechanical unit from Newman Machine Co. installs into gang ripsaws in place of the saw's original sleeve and requires minor modifications to the saw. The blades can be separated throughout the sleeve's length without limit between adjacent blades. Any combination of stack and space is possible and the company says any type of ripping can be accomplished with the system. Blades can be changed while the unit is installed in the saw.
The model 404 ripsaw from Mattison Woodworking Machinery Co. is equipped with a laser guide light for extended saw kerf position illumination, minimizing material loss during defecting operations. Also featured is a pneumatically-operated "quick-lock" rip gauge and an automatic anti-repeat retract system for the table mounted kickback finger unit.
The M3 gang rip saw from SCMI is available with a 60-hp motor and variable feed speeds range from 30 to 150 fpm. For added safety, the machine is equipped with emergency stops, four rows of kickback fingers and an amp meter. Automatic chain lubrication and high precision guideways ensure accurate material processing. Accessories such as short stock attachment and rubber chain are available depending on your application.
Atlantic Machine Corp. offers straight-line optimizing and a gang ripsaw in one machine. The CML SCA 450/2-R features heavy-duty construction, patented movable blades with corresponding laser lights system and increased safety with micro-switches on doors and five anti-kickbacks.
The series K 34 multi-rip circular saw from European Woodworking Machinery features feed rollers which are all driven, except for one, are available in five different designs: smooth, knurled, fluted with polyurethane rings and polyurethane coated. The feed system with a maximum of 11 top rollers and nine bottom rollers can be adapted to suit individual customer's requirements.
The SP2S planer/moulder/gang rip saw from Mida-USA Inc. can rip and plane in one pass at feed speeds up to 186 fpm. It has the maximum capacity in ripping of 4 1/2 x 24 in. Top and bottom heads are removable and interchangeable, and the company says carbide or high-speed steel knives can be used. Profile heads can also be attached to make certain profiles from rough random width lumber to a finished product in one pass.
The model 240 24-in. face planer from Northfield Foundry and Machine Co. Inc. features helical carbide cutterheads which are reported to offer low noise operation and high performance finishing in hardwood lumber.
The Martin four-side planer T90 from Eric Riebling Co. Inc. uses Tersa cutter-heads and offers quick cutter change. Features of the machine include variable feed speed, feed drive with automatic brake, separately adjustable pressure of infeed roller and automatic lubrication of machine table.
The Dimter OptiCut 304 optimizing cross-cut saw from Michael Weinig Inc. includes a new optimizing computer which is said to be 40 times faster than earlier computers. Added features include a patented "integrated waste gate" system which eliminates waste problems from the outfeed conveyor and a patented "torsion absorber" system increases sawstroke speed while dampening out end motion shock.
The lida OCS-251 optical cut-off saw from Pruitt Machinery Inc. is capable of cross-cutting lumber stock continuously while simultaneously removing various defects contained in it. The saw blade is housed within the machine for safety and is not exposed. Lines are marked on boards and a photo-electrical monitor detects the marks and cuts are made along the lines.
The model 216 pneumatic cut-off saw from Whirlwind Inc. is a semi-automatic cut-off saw and features magnetic motor controls, Baldor 10-hp TEFC motor, dust chute and double palm button controls. Optional equipment includes cutting blades, a 15-hp motor and 230V phase converter.
The Swing Saw from H & A Saws Inc. features two wear points for longer life, and parts interchangeability for easy repair.
The ST-9 resaw from Stenner USA Ltd. is designed to meet the requirements of the dry mill market. Its main features include simplicity of guarding, infinitely variable feed speed and large capacity. Other features include pressure saw guides, low noise, rigid fence, single main guard, grooved pulleys, simplified saw straining and no foundation pit.
The FR800 band resaw from Fortis Machinery Corp. is almost totally built from cast iron, including the one-piece cast iron body, cast iron wheels and pulleys, table and base. The table, which tilts up to 45 degrees, can be equipped with different configurations for feed work, four-speed or variable speed and corrugated or rubber feed roll.
The FJL 180 fingerjointer from Omga is composed of a shaping unit with an in-feed conveyor belt-hogging saw-vertical shaper-glue applicator. Fully automatic system with infeed conveyor belt and rotating table to line up, shape the wood on both ends by a single vertical shaper. On the tool carriage a hogging saw trims the ends first, then after the shaper, the roller applies glue on one of both ends.
The model 3870 fingerjointer from Industrial Woodworking Machine Co. is a complete low to medium production fingerjoint system. The system includes an automatic dual head shaper with 10-hp belt driven cutterhead spindles and 5-hp trim saws. It also includes an automatic glue application system, manual transfer conveyor, and automatic assembly machine.
Western Machinery Group manufactures a horizontal fingerjointing system in high, medium and low production rates. The company says the system is designed to use as much of the short blocks of wood as possible. The machines can be used in moulding and millwork operations, sawmills, glue lam beam plants and many other woodworking operations.
The clamp carrier/glue applicator from James L. Taylor Mfg. Co. presents new boards with glue applied in front of the operator when he needs them. Movement of the outfeed section of the machine and advancement of the conveyor are controlled by the programmable controller and work in harmony with the automated clamp carrier cycle. The system evenly balances the work load between the two operations and paces the overall rate of production.
Utilizing a crayon-based scanning system and optimization software, the Manually-Assisted Rip Saw Scanner Optimizer (MARS) from Lucidyne Technologies Inc. considers marked board characteristics and finds the most profitable saw solution. Using fluorescent crayons, the board is graded for defects and the scanner provides actual board contour information, as well as providing complete accountability and reporting.
"Superscan" board optimization from GreCon Inc. allows data entry of hardwood characteristics - in color - at a feed speed of up to 360 fpm. Accurately defines shades of red, blue, etc. as well as wood patterns to allow grading, cutting and sorting of like colors and wood fiber characteristics.
The Compu-Rip optimization system from Barr Mullin can find the maximum width usage of each board after the operator conducts a visual inspection of the board. The information displayed on the computer screen can determine such factors as board thickness, amount of cuts made and yield amounts.
COMPUTERS HELP CUT ROUGH MILL WASTE
Long associated with helping moulders, carvers, routers and panel saws meet flexible production quotas and high tolerances, computers are entering the rough mill to help wood-working operations optimize their yields through greater accuracy, while also helping facilitate more efficient handling of shorter runs.
"If a rough mill sawing system is off by 1/8 to 1/16 inch per cut, it may not seem like much," said Bob Winstanley, Dimter product manager for Michael Weinig Inc. "But over the course of a year, those small measurements can add up to be a substantial amount of money lost. A optimizing system can help a company recover those losses."
One of the most challenging aspects of integrating computerized rough mill equipment into an operation depends if employees can fully understand proper program operation through an effective training program.
"The learning curve to operating computerized optimizing equipment depends on the people who will be operating it," said Winstanley. "But it hinges on a supplier's commitment to offering its customers an effective training program to operate their machinery."
With raw material utilization playing a more crucial role in maintaining a competitive edge, computers in the rough mill will continue their role as tools to help maximize yields and productivity.
"The future of defecting boards will ultimately lead to complete computer scanning of the board," said John Foster, sales manager with Newman Machine Co. "The human grading decision will gradually be replaced by the computer's decisions. Computers will eventually scan the boards, mark the defects and send it to its respective machining operation."
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|Title Annotation:||includes related article|
|Publication:||Wood & Wood Products|
|Date:||Oct 1, 1994|
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