Nested-Based Manufacturing:
Material Optimization through Machine and Programming Software Integration

In a company set up with a Nested-Based Manufacturing cell, the sheets of material are placed on a CNC router and all finished components are machined complete in a single setup, without any material handling. The CNC router sizes, machines, rabbits, dados, grooves, bores, shapes, pockets and performs any other operation required on each part in the nest! The CNC router is equipped with a high volume vacuum pump (350+ CFM and 24"+ Hg.) that allows users to vacuum chuck nests of components without custom fixturing. The elimination of custom fixturing provides one-of-a-kind as well as high volume parts to be produced at the same rate. Nesting also provides maximum material utilization especially on shaped and non-symmetrical parts.

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In a Level I Nested-Based work cell a CNC router is driven by programs that contain nests of components that are generated by a CAD/CAM system such as AutoCAD and Router-CIM. Automated nesting software such as AutoNest is a great option for reducing the time it takes to develop nests of components. Higher-level work cells are essentially the same but utilize more extensive software to automate the design, nesting and machine code development.

In a Level II Nested-Based work cell product and component design is enhanced with a parametric extension for the CAD system. For AutoCAD users Mechanical DeskTop (MDT) will be used. Many cabinet shops and store fixture manufacturers will use cabinet design software as an automated solution for this level such as Cabinet Vision or CabNetWARE from Planit Systems.

In a Level III Nested-Based work cell the nesting and machine code generation is completely automated. This is accomplished with Second Shift software from CIM-Tech. For example, a Second Shift software package can be designed specifically for companies using certain cabinet design software that automatically extracts all *.dxf files needed for an entire job directly from that third-party cabinet software. It then creates the nests and generates all of the machine programs for the sheets of material to be machined. This could be done after-hours, unmanned - hence the name Second Shift. Many companies design products all day, load the designs into Second Shift, and return the next morning to have several days' worth of machine code developed and ready for the machining process.

In developing and justifying a Nested-Based work cell it is very important to consider the impact each level will have on your business. A properly equipped CNC router can machine a nest of parts in 5 to 8 minutes and it takes a designer/programmer set up with AutoCAD, Router-CIM and AutoNest 15 to 20 minutes to program a sheet nested with parts. It is also very important to focus on the production and programming requirements of your business and not the size of your business. For example, a large upholstered furniture manufacturer that produces a line of standard products in substantial quantities may never require more than a Level I Nested-Based work cell because they can afford the time to program and manually nest their work. If this same company needs to run high volume/low quantity (or JIT) they might require a Level II Nested-Based work cell. A small cabinet shop that produces all custom cabinets may require a Level III Nested-Based work cell.

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Begin your justification with a CNC router set up to function as Nested-Based work cell.

If your company:
1. uses 15 to 80 sheets of material per day and
2. 20% or more of your work is solid wood, surfaces, shaped parts, etc.

Begin your justification with a CNC router set up to function as Nested-Based work cell.

If your company:
1. uses more than 80 sheets per day and
2. has an accurate panel-sizing solution such as a CNC beam saw and
3. has a requirement for extensive horizontal boring and
4. 85% or more of your parts require boring but do not require routing

Begin your justification with a CNC router set up to function as Nested-Based work cell with a high-volumen Material Handling System.

Begin your justification with a CNC point-to-point boring machine and a CNC beam saw.

You should also consider two CNC routers set up to function as Nested-Based work cells.

Note: A second Nested-Based work cell is relatively inexpensive to implement because the computer system, software and learning curve is already taken care of and doesn't need to be duplicated.

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• CNC routers offer much greater workholding and machining capacity than point-to-points. The end results from a CNC router will be superior feed speeds, better finish, and less machine-related down time.
• A CNC router offers faster setups, better workholding and better machining capabilities for machining surfaces. Flow-through vacuum holddown provides fast setup on large parts that require through-cuts, perimeter sizing and/or edge shaping.
• CNC routers are the only effective machines to produce miter fold components with accurate miters for folding. Uniform depth-of-cut is critical for machining tight-fitted joints.
• For high volume MDF production and the ability to machine multiple parts simultaneously, a CNC router is a better machine selection. For MDF door production requiring tight tolerances, accurate tool blends or diamond tooling, a CNC router will outperform a point-to-point machine. For lower volume MDF door production, either a CNC router or a point-to-point will work well.
• CNC routers can be set up for machining several different parts at one time to provide production of full assemblies. It is also the best machine to produce nested parts on a single sheet.
• Point-to-points offer the best throughput for JIT production of 32mm components that are pre-sized. The point-to-point's greatest attribute is increased drilling capacity.
• CNC routers with appropriate head configurations can machine multiple parts simultaneously. Routers equipped with multiple boring blocks offer some of the production capacity of a through-feed boring machine with the flexibility and quick set-up features of a point-to-point.

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If your company uses 15 sheets of material or more per day and/or you have two full-time employees performing sawing, routing and shaping operations you should consider a Nested-Based CNC work cell. Just because you begin the justification process with one type of production method doesn't mean you shouldn't consider alternatives for your company. For example, should your company have extensive horizontal boring requirements it may still be appropriate to design a Nested-Based work cell that includes a bore/dowel insertion machine. Because the machining cycle in a Nested-Based cell is relatively long, an operator has four to eight minutes in which time he/she could be horizontal boring and doweling panels.

For the purpose of justification always use a lease payment because it is easy to calculate and will allow you to quickly develop a monthly machine expense. Keep in mind that it doesn't matter if you lease a machine, finance it or pay cash and forgo the monthly interest on your money - there is a monthly expense associated with your machine tool acquisition. An equipment lease may provide you with some significant tax advantages by allowing you to write-off your monthly payments as an expense while reserving your line of credit with your bank for cash flow. Monthly lease factors change almost daily; check with your machine tool distributor for the current rate.

Machine Justification Components:

Two Person Labor
If you have two or more employees sizing panels on a saw, machining rabbits, cutting dados, sawing back grooves, boring holes, shaping parts, machining pockets, handling parts from station to station or any other operation that could be replaced by a CNC router, you should be able to justify a Nested-Based work cell. For example, If your lease payment is $3,960.00/month your annual expense for the Nested-Based work cell is $47,520.00. If your billable shop rate is $30.00 per hour you will only have to replace 1,584 hours to justify a Nested-Based work cell. This is less than one person! If you replace (or displace) one person ($62,400.00/year at $30.00/hour) your company will pay for the Nested-Based work cell plus make an additional $14,880.00 in profit the first year. If you replace two people your additional profit will be $77,280.00 and three people will be $139,680.00 and so on. Most business owners and/or managers don't realize that they are already paying the equivalent of machine payment in wages.

Fifteen Sheet Daily Use
If your company uses an average of more than fifteen sheets of material daily, you can justify a Nested-Based work cell as follows: A Nested-Based work cell will produce a panel every four to eight minutes with one operator. With an eight minute cycle time, fifteen sheets of material can be produced in two hours, leaving the rest of the day for assembly. Your cost per sheet processed is minimal, as well. If you use the lease number from above ($3,960.00/month) and divide it by your monthly material consumption (300 sheets), your cost to process a sheet of material turns out to be $13.20 plus 40 hours of labor and overhead. If you use a labor rate of $30.00/hour your total labor cost to process 300 sheets is $1,200.00 The numbers become even more impressive as your volume increases and your cycle time decreases.

Can't Find Good Help
It is very difficult to find good employees. Well-trained people are in very high demand. After you have spent the time and money to train an individual they soon become the target of other employers. A Nested-Based work cell will provide your company the ability to have fewer higher-paid employees that have a future with your company and are less likely to leave. A Nested-Based work cell also allows you to be far less dependent on even your best employees because the required job skills are definitive and trainable. As you can see, if you need to hire an employee, you already have a great justification for a Nested-Based work cell.

Material Handling
Material handling is an important reason for the justification of a Nested-Based work cell. In most cabinet shops and store fixture manufacturers, shop personnel spend as much, or more time handling, stacking and de-stacking parts as they do processing parts. This can be quickly identified in your shop if there are stacks of parts in front of and in back of several work cells. Keep in mind that on a Nested-Based work cell, an operator loads a sheet on a CNC router, hits the cycle start button, and then has four to eight minutes for secondary operations. There is no material handling in a Nested-Based work cell.

Setup
With the high-volume vacuum pump of a CNC router and flow-through vacuum work holding, there is virtually zero setup time in a Nested-Based work cell. This work cell can literally produce one part at the same rate it can produce one hundred. This is a critical advantage over manual machines that need to be adjusted for every part or series of parts. This also has a big advantage over a CNC point-to-point machine because there are no individual programs to write or load, no rails to adjust, and no special considerations to be made for through-cutting. Keep in mind that no machine in any shop makes a dime for it's company unless the tool is into work! If a machine is down for programming, setup, maintenance etc. it isn't making money.

JIT
Because the Nested-Based work cell has near zero setup, it provides Just-In-Time (JIT) manufacturing capabilities. This allows a company to become a great deal more responsive to fluctuating sales while at the same time substantially reduce inventory.

Rework
Rework is almost a non-issue in a Nested-Based work cell. Because this work cell can efficiently drive production to a lot size of one, damaged components can simply be re-introduced to the system.

Floor Space
A Nested-Based work cell can function in as little as 250 square feet. This takes up far less floor space than a beam saw and CNC point-to-point combination, or several smaller machines. Operating in a JIT environment also reduces the space required for inventory of components ready to assemble, and stacks of work in process components at various work cells.

Predictability/Scheduling
Because the part quality and output of a nested based-work cell is so predictable, scheduling is very easy. The machine sets the pace and produces same number of high quality components many hours per day, no matter what day of the week production occurs.

Peaks in Sales
Very few of us work at a company that doesn't experience fluctuations in sales and backlogs. Because of the raw production capacity of a Nested-Based work cell, a few hours of overtime or one operator on a second shift can keep up with the most radical spikes in sales volume. The type of people that you will need to add, if any, will be lower-skilled employees (or temps) primarily for assembling.

Quality
Increased quality is a given in a Nested-Based work cell. Every single edge is machined instead of saw cut, and parts are sized to the accuracy of a CNC router, which is far more accurate than a saw. There is also no potential of operator error because the CNC router is completely processing the components. Edge banding a machined edge is also superior to banding a sawed edge.

Assembly
Because parts produced in a Nested-Based work cell are extremely accurate, assembly is a breeze. Many companies report that they justified a Nested-Based work cell on the labor savings for component manufacturing, but that the reduced labor in assembly is actually as great, or greater, after work cell implementation. This is an extremely hard thing to quantify prior to implementing a Nested-Based work cell. You will see significant savings in assembly time.

Peace-of-Mind
Higher margins, less labor, more coordinated production, better quality products, and increased general predictability provide a great deal of peace-of-mind for company management and their employees through Nested-Based Manufacturing.

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