Industry Flocks to Nesting

Suited for small- and mid-sized production shops, as well as large shops with custom applications, nested-based manufacturing accomplishes with one machine, in one step, what otherwise takes many machines to perform in multiple steps.

By Karen M. Koenig

     
 
Nested-based manufacturing enables flat panel producers to cut various geometric shapes from a single sheet, in a single step. A CNC router is used to machine complete parts for cabinets, residential furniture, store fixtures, etc., including sizing, rabbeting, dadoing, grooving, boring, and shaping. Photo courtesy of Stiles Machinery.  
     

It’s often considered simplification at its best. Nested-based manufacturing (NBM) gives flat panel producers the ability to cut various geometric shapes from a single sheet, in one easy step.

Sizing, rabbeting, dadoing, grooving, boring, shaping, etc., are all performed on a CNC router equipped with a high-volume pump. This allows for vacuum chuck nesting of components without custom fixturing. But while not for everyone, NBM is suited for use by small and mid-size production shops, as well as large shops with custom applications.

     
Competition Helps Drive the Nested-Based Manufacturing Market

One of the driving forces behind the nested-based manufacturing (NBM) phenomenon can best be summed up by two words: increased competition.

“There are several areas of our industry which are focusing on NBM, however the kitchen cabinet and upholstered furniture frame people are leading the way,” says John Ridgway, operations manager at Anderson America. “This is principally because their markets are increasingly competitive and profit margins are very tight. NBM is the only way to survive in these areas.”

Dave McFarland, Heian product manager, Stiles Machinery, agrees, adding that, “Medium and large companies are more likely to adopt this process as lot size requirements continue to be driven down.”

“NBM makes it easier for a small company to compete with less people,” says Kris Hanchette, vice president of sales, MultiCam. “Because NBM allows parts to be fully nested on a sheet, you will get a better material usage and less waste than you would with a saw and a point-to-point, helping a mid-sized company become more efficient and cost-effective. A large company with multiple machines will greatly reduce errors and the amount of floor space needed since the parts will need to be handled less.”

In addition, Hanchette adds, “The machines are getting faster, easier to use and more cost effective. It is all about working smarter and not harder. Most shops cannot afford to compete if they do not go NBM.”

Software improvements are also driving the NBM market, says Danny Thompson, Southeast regional manager, Holz-Her U.S. “One of the primary forces moving the NBM concept forward today is the improved integrated ‘nesting’ software that is imbedded into the ‘design’ software from design software writers. The other is the growing desire of shop owners to have more control over not only the design of their cabinets and fixtures, but also the actual production process.

“One of the two segments I see NBM being most utilized by is the specialty fixture and display manufacturers because they are already utilizing various cad/cam design programs for their work,” Thompson continues. “The other is the mid-size custom cabinet manufacturers for much the same reason, except in their case it is the cabinet design programs they have been using for the past 10 to 12 years that now have upgrades to capitalize on the integration of NBM in the CNC modules.”

Karl Frey, vice president of SCM Group’s Routech Division, says, “The primary advantage of the process is how quickly you produce machine code and machine the finished parts after you receive the order. The process, from the finished drawing to finished parts, has seen powerful changes due to nesting and CAM enhancements. As a result, you can process parts quicker with less human intervention. The programmer is basically driving the shop floor for component piece manufacturing.”

— Karen M. Koenig

 
   
     

According to Dave McFarland, Heian product manager, Stiles Machinery, NBM is packaged as a complete manufacturing system. Included are software, tooling, fixturing, the CNC router, material handling, installation, training and integration.

“(NBM) offers several advantages over conventional processing,” says Ken Susnjara, chairman of Thermwood Corp. “First, the capital investment for an automated system is generally less. Using traditional methods, both a panel saw and some type of point-to-point machining center are required. With nested-based, generally a large table CNC router becomes the only major investment.

“With NBM, yield can be better if the proper technology is used,” Susnjara adds. “NBM does not require parts to be aligned along ‘cut lines’ as is required for panel saws. Also, odd-shaped parts such as tops and decks for corner cabinets can be interlocked rather than having to be first cut into rectangles with the saw and then cut to shape using the CNC.”

“NBM also saves a shop time and money by reducing errors and streamlining processes,” says Kris Hanchette, vice president of sales, MultiCam. “Each time you move a part from one machine to another, you can introduce error. NBM allows the part to be fully processed on the CNC router. The user puts a full sheet on the machine and pulls off finished parts that are ready for assembly.”

Small and Large Shops

In addition to cabinets parts, NBM can be used to manufacture store fixtures, residential furniture, MDF doors and other flat components. “All of these items are able to be ‘kitted’ for production,” says McFarland.

“(It is ideal for) one to 20-person shops that need to process 15-plus sheets per day,” says Craig Sexton, national router product manager, Biesse Group America. “These cells work excellently with HPL, MDF, plywood, OSB, solid surface, veneers, any type of non-ferrous metal, plastic, acrylic, etc. Although currently it’s primarily being promoted in the wood industry, this style of production has been around 20-plus years in other industries.”

According to Dan Radusinovich, regional sales manager, Masterwood Group USA, a potential nested-based manufacturer is one which “is already using some type of design software; is willing to spend additional monies on necessary design software; is not currently operating a high-production level saw; and is caught in a labor shortage with not enough employees to process all the parts.”

“NBM has potential advantages for all sizes of companies simply because parts produced by nesting cost less,” adds Robert Alsup, National Komo Technology Center program director, Komo Machine.

“The revolution brought to the industry by NBM is that small companies can now be as competitive as the large ones. In fact, the small companies may be getting an unfair advantage because they are not experiencing the high fixed costs that follow large facilities with lots of people,” Alsup continues.

     
Is the NBM System Right for You?

Nested-based manufacturing is not for everyone, say industry experts.

“NBM is a manufacturing approach that must be reviewed and judged on its economic merits, the same as cellular manufacturing and high production manufacturing,” says Mike Cox, Bussellato product manager for Delmac Machinery Group.

To determine if a company is a candidate for NBM, Cox suggests asking the following:

• Is the customer ready/willing to use the CNC machining center as his main work center?

• Does the customer have or is prepared to use cabinet design software and nesting optimization algorithms?

• Does the customer presently have a beam saw?

• Does the customer have limited production potential and limited goals, i.e., one to five kitchens per day?

• Will he be satisfied to have the output of parts from a production CAD program as his primary design/programming entity?

“It depends on the customer’s needs for now and the future,” says John Ridgway, operations manager at Anderson America. “A small cabinetmaker who does not project or welcome increased production growth is better off staying with traditional production methods.”

 
   
     

John Ridgway, operations manager at Anderson America Corp., agrees. “A small company will benefit from the addition of NBM the most as it will broaden the horizons of the complete operation. Adding NBM will boost overall output and efficient production while reducing overhead and labor costs.”

“Small shop owners are quick to realize the need for competitive leverage,” says Michael Dupont, Northwood Nestech product manager, Altendorf America. “Technology is their lever. NBM is comparatively inexpensive on a per part basis. Also, the flexibility that NBM affords permits the small shop to diversify easily with very little incremental — or no — increase in investment in personnel or equipment, other than software and tooling in most cases.

“With larger manufacturers going offshore, there will be a rising need for domestically-produced products that have short lead times,” Dupont continues. “Automating a small shop to accommodate these needs is an ideal solution. Coupling a computer and manufacturing software to computer-controlled machinery makes the small shop very competitive. Communication between these small shops and their customers will make it possible for the shop to be the virtual factory from which the customer gets product, components, etc.”

Karl Frey, vice president of SCM Group’s Routech Division, agrees. “Small companies can purchase one machine to do all or most of their machining operations. In many respects the technology evens the manufacturing playing field between small and large companies due to the high productivity,” Frey says.

“Mid-size companies,” he adds, “can consider using the NBM method to compartmentalize operations where a programmer and operator are a team, with the second team consisting of finishing and assembly. Large companies can consider NBM for all their custom operations. If they want to make all their product lines custom, with quick ship programs, NBM has many positive benefits to consider.

“As the market goes to mass customization for panel processors, the benefits of NBM will be more readily noticeable,” Frey concludes.

Pros and Cons of the System

Reductions in programming, in-process inventory, material handling and in the possibility of positioning errors from one process to another, are just some of NBM’s benefits being touted by machinery manufacturers.

“Small companies eliminate the number of processes, number of hands on a piece and number of times a part needs to be handled. Those customers with limited space and payroll levels will most greatly benefit from the one machine, one payment, one man and one footprint advantages offered by NBM,” says Don Dixon, regional sales manager, Masterwood. “Medium and larger companies benefit from controlling the yield per panel better through the high optimization of the NBM process.”

“I believe (another) key point to sell the customer on is just-in-time production and labor savings,” says Steve Hillis, CEO of CMS North America.

     
The Basics Behind Nested-Based Manufacturing

In general, nested-based manufacturing (NBM) is typically used by cabinet, residential furniture and store fixture manufacturers and other flat panel processors, although “anyone who does one-of-a-kind (custom) type production out of sheet goods is a candidate for NBM,” says Craig Sexton, national router product manager, Biesse Group America.

Using a CNC router, all vertical operations, including sizing, rabbets, dadoes, grooves, bores, edge profiles, pockets etc., can be accomplished in a single cycle, Sexton says. Horizontal operations, however, cannot be performed during NBM. “These operations are being done on traditional machines and/or they are being reintroduced to the machining cell on pods,” he says.

According to Sexton, the average machining time to complete a nested panel is minutes. “To accomplish all the vertical machining operations to a panel will take ‘high-end’ machines 4 to 6 minutes and on some of the ‘entry’ type machines 10-plus minutes.

“Using a 6-minute machining time with a 4-minute load/unload time equals six sheets/hour x 7 hours = 42 sheets/day with one operator. It’s very easy to see how with a ‘high-end’ machine with the right options you can easily produce 70-plus sheets per day with one operator,” Sexton adds.

Typical tooling for the process is 3/8-inch or 1/2-inch three-flute compression spirals. “These tools liked to be pushed fast — 1,000 to 1,500 ipm — which allows the heat to evacuate with the chip. As a rule of thumb, these tools will last one to 1-1/2 units before they have to be re-sharpened. Usually they can be re-sharpened three times.

“Having the right front-end parametric software for a particular application is the driving key to make this all work,” Sexton adds. “This element needs to be fully implemented prior to investing in a NBM machine.”

 
   
     

“With this method, parts can be produced as needed for a particular item, such as an upholstered sofa or chair, or even a complete custom kitchen. The labor savings come into play by taking the sheet stock to one machine. There are no additional steps needed before the panel is placed on the machine for processing. The manufacturer knows exactly where the part is in production and when it will be completed. It removes the guesswork on when the production pieces needed for final assembly will be available,” Hillis says.

One benefit of NBM, Hanchette adds, is that “shops can work out all the details for their customer and even walk them through a room on the computer before they ever cut a part.”

“The benefits go across the board for all company sizes,” adds Dupont. “(They include) a small footprint with a considerable amount of capability, typically one operator for the full operation, great flexibility with very little set-up time between runs, consistent accuracy and repeatability that is less dependent upon the operator, and the potential for savings based on yield improvements. Even the largest companies can use NBM in flexible work cells or ‘custom’ shops.”

However, manufacturers say, NBM may not be for everyone. “As shops increase in production requirements, they can find NBM to be too limiting in the number of panels they can efficiently process,” comments Danny Thompson, Southeast regional manager, Holz-Her U.S. “In shops that have more uniform parts, using a saw that can cut books of two or more may be more practical.”

Susnjara agrees. “(In) small- and medium-sized companies where a single CNC router running NBM will suffice, the lower investment makes this the best choice. (However,) larger companies running large volumes of standard cabinets might find that the high throughput of a CNC panel saw feeding several point-to-points may offer a better choice.”

Another consideration McFarland mentions, is that horizontal router/drill work must be done off-line. However, he adds, “a dedicated horizontal machine can be run by a CNC operator during the NBM cutting cycle.”

     
 
CNC routers used in nested-based manufacturing feature larger and improved vacuum pumps, as well as better monitoring as sheets are machined. Photo courtesy of Delmac Machinery Group  
     

“Construction methods may also be affected, requiring some retraining of the labor pool,” Dupont adds. “Incorporating an off-line dowel drilling and insertion machine can offset the impact. In fact, while the machine is running a sheet, the router operator may dowel parts that were just removed from the machine, thus maximizing his time.”

“Understanding the processes of both standard manufacturing and NBM is the first step in overcoming these issues,” says Hillis. “Understand when to use NBM and when not to. When purchasing machinery, make sure it is capable of being used for NBM and for standard processing methods involving hard fixturing. Flexible machinery can, with easy changeover and setup, reduce the negative aspects.”

Software and Other Challenges

Overly complex software, hold-down limitations and dealing with partial sheets were the top three “negatives” facing early NBM users.

“Without a doubt, software to create the G-code was the greatest hurdle for NBM as a manufacturing concept,” says Mike Cox, Bussellato product manager, Delmac Machinery Group. “The software has since advanced from needing a computer guy on staff and running all night (second shift), to being able to be run by typical cabinet shop personnel.”

“Another major problem involved the time required to turn the ‘design software’ parts into code the routers could make,” adds Thompson. “This was resolved with faster nesting software that reduced the time per part required to nest the parts on a sheet from 7 to 9 seconds per part to less than 4 seconds per part.

“The other major problem, which can still be an issue, is the ability of some machines to hold small parts in place. This has been solved by some router and software companies in a variety of ways,” Thompson says. Solutions include: larger vacuum pumps and vacuum supply lines, larger plenums under the vacuum tables and dual zones for vacuum tables. Also improved are: the monitoring of inches of mercury of vacuum as sheets are machined; the optimization of cutting processes via software to always cut the smallest parts first; and software designed to place small parts to the middle of sheets.

     
Advice Before Buying

Robert Alsup, National Komo Technology Center program director, offers the following “plan of attack” for companies investigating nested-based manufacturing.

Alsup recommends visiting a machine installation with a specification as close as possible to the machine you will be using, preferably with the same design software. Watch the machine’s movements, how it changes tools, its ease of operation, etc. Also, observe the material’s loading and unloading process for a clear picture of how the software is involved in the manufacturing process. Also ask:

1. How long did it initially take to make the parts on the machine?

2. Were you presented with a realistic expectation of what it would take to implement this new technology?

3. If you had it to do over again, what would you do differently?

“Finally, require the machine supplier to cut your parts while you watch, with the software that you plan to use. It must be ‘live,’ not a canned demo. If possible, design a simple case, produce the machine codes, cut the parts on the machine and see if the parts fit. Have them demonstrate the complete operation of the machine, control operation, tool insertion, software setup, etc. Some of the parts in the nest must be small so you can see if the machine’s vacuum system is adequate.

“Never forget the First Rule of NBM,” he says. “If the parts move, nesting doesn’t work.”

 
   
     

Dave Wright, Masterwood regional sales manager, also notes improvements in vacuum systems. “The vacuum systems were rarely adequate in the early years. Now, smaller and more compact machines offer proper vacuum, a work area which allows for easier part access and part removal. (Also,) early flat table routers didn’t have the boring heads or the feed speeds which are available now,” Wright says.

“(Another) truly difficult challenge was the requirement to deal with partial sheets, sometimes called ‘drop,’ left over from a job,” adds Susnjara. “This material represents real cost. However, developing a simple method of handling it presented a major technical hurdle.

“We had to develop an electronic description of all the parts we wanted to make, send this to the CNC machine control, scan the drops we wanted to use, have the machine control develop the nests for the exact material sizes being used and then develop the required CNC programs to cut those nests. We were able to develop a method for defining an area on a sheet that is not usable. The control then nests around this area using only good material.

“A cabinetmaker may now be able to purchase material with surface defects at a substantial discount and automatically nest around the defects, dramatically reducing material costs,” Susnjara adds.

Further Machine Developments

In addition to the necessary developments in software and vacuum, the machines themselves continue to show improvements in speed and material handling capabilities.

“On the machinery front, the advent of ‘flow through’ fixturing, dynamic tool change and the adaptation of multi-spindle drills to CNC routers, virtually eliminated machine set-ups. Every sheet processed on the machine could be a different group (nest) of parts,” Alsup says.

“Concurrently, the design software programs developed the ability to generate electronic part drawings automatically. The integration of software and machine technologies provided the ‘zero set-up’ basis for NBM,” he adds.

“To be truly effective,” Hillis says, “the machine has to be able to hold down small parts positioned at any angle in the nest. This is an area that the original style of NBM machines,the roller hold-down type, had problems with. The traditional roller hold-down machines work well for parts positioned lengthwise on the table, but they do not fully address the complex nests that can be created with today’s software.

“By requiring the end user to position parts in one direction material, yield can be lost. With the new software capabilities, the machine is required to cut both small and large parts positioned at any angle on the table. To do this, high volume vacuum pumps were added to the routers along with a vacuum system and plenum that would accommodate the air flow. Couple these features with the new higher cut speeds available and you have a machine that is ideal for NBM,” Hillis continues.

Radusinovich adds that increased horsepower, higher feed rates and an increased capacity in the working zones have also improved the process. On the horizon, he says, are more advanced bar coding capabilities plus more routers with close to zero chip-to-chip time.

Cox details further developments. “Since NBM requires the router motor to be cutting for much longer periods without rest, liquid cooling of the spindle has become a necessity to preserve bearing life. In addition, improvements have been made in material handling systems to facilitate the unloading and loading process to increase the production output. A machine that can rout at 2,500 inches per minute but sits idle while being loaded and unloaded is a waste of technology.

“Full tool coverage is another aspect of NBM that is often overlooked,” Cox adds. “If a tool can’t reach, then the software must alter the nest to accommodate the machine tool. Yield and processing time will suffer.”

“Control technology,” Dupont says, “has also provided accuracy and repeatability, even at high machining speeds. Digital servo drives precisely model and control the axes and accurately keep them synchronized at all times.

“Newer generation controls with PC front ends make it easy to incorporate the machinery into the factory network. This facilitates sharing information between the design office and the factory floor. Errors are reduced, turnaround time is reduced, and numerous other benefits follow,” he continues.

“The industry continues to embrace this new technology at an amazing rate,” adds Ridgway. “Future developments will always be based upon a sound technological foundation and will proceed along that direction. Stay tuned for more on this in the coming months.”

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