Bender tooling choice not to be taken lightly
May 13, 2008
Fabricators have two broad choices in the bend tooling they select: standard or custom. Using standardized tooling provides cost-effective versatility. A well developed tooling inventory can accommodate nearly any bending job. On the other hand, custom tooling is designed for speed and efficiency. Customized tools make one part and one part only as fast as possible. The trade-offs boil down to time and money: standardized tooling requires more time to set up but costs less. With custom tooling, changeover is quick, but the tooling costs more.
Contrary to a popular misconception, the output of durable goods in the U.S. has been on an upward trend for decades. This growth is interrupted by intermittent, short-term slowdowns, of course, but the fact is that the U.S. continues to be a productive nation, and its output continues to climb. The common observation that "we don't make anything in the U.S. anymore" simply isn't true.
On the other hand, surviving in manufacturing keeps getting tougher. Intensifying domestic and foreign competition, budget cuts, shifting customer requirements, and changes in consumer demand have cut into margins, making it more difficult than ever for manufacturers to survive, much less thrive. Most job shops are up against tight deadlines and must act quickly and efficiently to secure business. Time is money, and whether you have the tools to get the job done on time can mean the difference between turning a profit and losing your shirt.
So how do you choose the right tools? Is it better to design custom-made, specialized tools for each job to maximize throughput, or does it make more sense to order standard tools that can pay for themselves time and time again? Each approach has certain benefits, and exploring them thoroughly is the first step in making an informed decision.
The most experienced job shops have seen their share of ups and downs. They know how to react to any situation and what tools will be needed to get a job done. New companies need the help of experienced tool- and diemakers to arrive at the best solution. Good tooling designers should be able to work seamlessly with these companies and approach a difficult application objectively to present the best solution that addresses all of the key requirements.
The most common approach to tooling is to use existing tools if they are in good enough shape, and to buy new tools if they are not. This is probably the simplest method, but it is very short-sighted and leaves much room for improvement. Collecting a large inventory of tools can prepare a shop for a wide variety of jobs, but some applications require tools with more customization than a large tooling inventory can provide. Often custom tools must be ordered specifically for that project. Purchasing project-specific tools for each application is an operator's dream, but it is not always practical to build the cost of the tools into the quote. The reality is most bend tools are designed to accommodate the current project as well as future projects to help offset the initial investment. A little bit of forward thinking and planning can ensure that bend tools can be used for many years to come.
Some unique jobs are too costly or too complex and will never work with standard tooling. These applications require custom tooling that may never be used after the project is complete. Where the line is drawn between standard and custom tooling is the question.
Standardization removes many of the roadblocks companies encounter as they adapt to changing market conditions. This is especially crucial for companies that experience a high level of growth or a high level of employee turnover. Developing tooling standards can sound like a daunting task, but it can be quite simple if they are established early and followed religiously. When it comes to tooling, standardizing enhances versatility. Large production runs can be produced on two similar machines. Broken or worn tools are easily replaced with tooling from other machines or in other cells. Quoting and designing tools take just minutes or a few hours when using applicable standards. Standardization isn't a single, all-encompassing concept. Fabricators have a choice in the level of tooling standardization.
Experience Counts. One benefit of standardization is that it reduces the shop's dependence on experience. Losing a senior bend operator can be a big setback, and it can take a shop many months to rebuild the lost expertise. Trained bending operators are hard to find and can be pulled away with little or no notice. Experienced benders are worth their weight in gold, and passing that experience along to entry-level operators takes time. Having a well-documented set of tooling standards and policies can smooth out these bumps in the road. New employees can hit the ground running when they have a system to follow. There is no replacement for experience, but easy-to-follow standards and documentation are the next best thing.
The first and simplest level involves developing a set of standards for every set of tools purchased for the shop. These standards include establishing interlock dimensions; common mounting patterns; and universal sets of grip lengths for long, medium, and short bending applications. This builds redundancy into the tooling inventory and allows for the greatest amount of flexibility. If all the machines in a shop are the same make and model, choosing standardized tooling is an easy decision. In reality, a job shop has a variety of machines purchased at different times, under different circumstances, with different budgets.
One Size Doesn't Fit All. The next level of standardization involves the bending machines themselves. It may require some foresight, but with a few adapter plates, each machine can be set up to run the same style of tooling. Once these adapters are in place, the job of ordering and assigning tools to a machine becomes much more straightforward. When all the machines are set up to run with identical tool mounts, future tools can be ordered with common keys, through-holes, and inserts. Suddenly the shop's capacity swells because each machine is capable of running many styles and sizes of product. In addition, high-volume jobs can be run on several machines at one time for faster turnaround times.
A case in point is a job shop that has been buying tools with the same set of standards for 15 years. It now has a well-stocked inventory of tools and a database with photographs to track the entire inventory. This shop has several styles of machines with varying tool mount patterns, but a common set of adapters unify the design. All of the tools were designed with the same standards to use a common set of adapters. Quoting jobs is fast and easy because they know what tools they have and they know that they can run the parts on any machine. This degree of flexibility and versatility keeps this shop ahead of the competition on every job they produce.
The Edge of Standardization. As more and more standards are developed and implemented, the line between standard tooling and custom tools begins to get blurred. The standards start to become custom for that specific company. Reach-adjusted (RA) tools are a good example of this. RA tools are designed as a complete set of tools to drop-mount onto a machine without any adjustment (see Reach-adjusted Tooling sidebar). If an entire family of tools is purchased as RA tools, a bend operator can change an entire toolset from one job to another, and start producing parts in a matter of minutes instead of hours. Again, this approach requires forethought and an upfront investment, but if the tools are well-designed, the time savings makes the extra cost worthwhile.
Many fabricators purchase RA tooling when purchasing a new bender, and this practice is becoming more common. The fabricator specifies the tube sizes, bend radii, and other relevant information ahead of time, and the machine builder supplies a bender that is ready to go. The entire tooling package is designed to work on one particular machine, and it is intended to stay with this machine. This is a perfect example that shows how highly standardized tools begin to evolve into customized tools.
Jobs that are high in volume or that have an increased level of difficulty beg for customized tooling. If reducing setup times and eliminating operations are the goals, then customized tools are the method for reaching those goals. Tooling customization can take many forms. Stacked tooling, custom grips, compound grips, hole punchers, cutters, and roll forming tools are examples of tools that deviate from the norm. The common theme among these examples is that the tools are carefully designed for very specific applications.
The purpose of any customization is to eliminate time-consuming steps in the manufacturing process. For instance, compound grips can eliminate cutting and welding operations. Stacked tools can reduce setup time or in some cases eliminate tool changes. Punching and saw cutting eliminate extra handling by the operator. All of these customized applications require careful feasibility studies and a thorough cost justification analysis.
One aerospace component manufacturer has replaced an entire cabinet filled with tools using a single triple-stack setup. With this stacked tooling, a single machine handles three tube diameters and three bend radii. These are tight-tolerance, RA-type tools, which eliminates the need for fine adjustments. Switching between any number of jobs that use these three sizes is a matter of pulling up a different program rather than physically changing the tooling on the machine. In addition, the tooling is designed to run without a mandrel or a wiper, eliminating the time associated with setting up those additional tools and applying a lubricant.
When purchasing custom grips for a multibend part, fabricators must pay close attention to the distance between bends (DBB). In some applications, the DBB is shorter than the prescribed grip length for the application. One option to resolve this issue is to use an aggressive grip surface, but that has the potential to mark the tube. Another option is to use compound bend tooling. Compound tooling (often called bend-on-bend tooling) can speed up production by reducing setup times, but the tooling generally costs more.
Many complex parts are made by cutting and welding together several bent components. This involves producing all the bent parts individually, carefully cutting each bent part to a finished size, fitting the parts together in a complicated jig, and finally welding the parts together. Jobs like this are prime candidates for compound grips. Increases in efficiency may be realized after implementing custom tools designed to eliminate cut-and-welded parts and manufacturing them in one seamless bending operation. The decision to invest in these tools is usually made after carefully considering the machines available to produce the parts and the quantity of parts in the production run.
When a bent tube has a centerline radius that exceeds the machine's capacity, it is necessary to explore alternative strategies. Roll forming (or push bending) tools are now becoming an attractive alternative. In the past roll forming tools were used on separate machines that often had been relegated to a back corner of the shop. Only the seasoned veterans knew how to get a good bend on the first try. These days roll forming tools have stepped into the spotlight. Many new CNC benders have roll forming capabilities as a stackable option. Advancements and improvements in the machine controls have simplified the setup and increased the repeatability of these tools. Roll forming tools are becoming a much-needed option on most new machines.
If a job shop has many applications like the ones described previously, the focus should shift away from tooling and toward the machine's capabilities. CNC machines can greatly improve throughput and versatility, and multistack tools take it to the next level. Increased speed and accuracy and decreased noise and power consumption are key benefits.
So now the question is, How do I decide which approach is the best? As with most difficult questions, the answer usually comes down to time and money. If most of the jobs running through a shop are low-volume with a high level of variance, developing standards probably make the most sense. These standards help keep the shop flexible, organized, and ready to take on the majority of projects quickly and efficiently. If, on the other hand, the jobs tend to be high-volume runs and the product mix is relatively stable, specialized tooling can eliminate time-wasting steps and increase repeatability.
Most shops already use a combination of these two types, standard tooling for some jobs and custom tooling for others. Pulling together the most important features of standardization along with the added benefits of customization efficiently is the key to success.