Scope Maker Sights-In Turning Process

Working toward goals of improved efficiency and quality, this Oregon rifle scope maker looked holistically at their manufacturing operation and matched appropriate processes and technology to each operation. Some improvements arevery simple, and some are quite sophisticated.

Article From: 9/1/1995 Modern Machine Shop, ,

Process is the coming together of factors needed to produce an output. It can be as specific as spinning a nut on a bolt or broad as assembling a car. Generally speaking, processes represent links in a chain of manufacturing events that result in product out the door.

All manufacturing enterprises are bound by the processes they use to make their products. It doesn't matter if the shop makes parts under contract for other businesses, is a captive of a larger enterprise, or manufactures and markets a product of its own. How well things get made is strictly determined by the effectiveness of the processes used to make them.

Process is also where the art of manufacturing branches from the science. Fundamentally, all metalworking shops work with similar kinds of tools. They each have equal access to the same technology be it tooling, cutters, machines, software or materials.

It's how these tools are applied to the manufacturing process--the steps between raw material in and finished product out--that is an individual company exercise. It's based on the very factors that differentiate one company from another--capability, culture, market demands and others.

Leupold and Stevens, a Portland, Oregon manufacturer of high quality rifle scopes, is an example of a shop that's reaping benefits from its process improvements. Using a systematic approach of defining a process, applying the right technology and then giving the workers skills and accountability for their part in the process, Leupold has seen its direct and indirect manufacturing costs significantly reduced. It has also seen product quality and manufacturability improve.

We talked to Bill Owen, vice president of manufacturing, about what Leupold has done, how they did it and where they're going from here.

Gone Global

Leupold and Stevens manufactures a line of premium rifle scopes. Much of the machining they do to make their product revolves around the turning process with various amounts of milling and drilling thrown in. Some of the milling and drilling is done on turning centers, and some is done on machining centers.

Process determines what goes where.

They participate in the global economy as both seller and buyer. Their rifle scopes and other products are marketed worldwide and compete with the best offerings from Germany and Japan. They also use the global marketplace for buying equipment. They go out to find suppliers of technology that are best for their manufacturing process application. But they are not about to abandon responsibility for their manufacturing processes to those suppliers. They keep that in-house.

Impetus For Improvement

Global market participation cuts both ways. The critical optics used in Leupold's scopes and other optical products are vendor-supplied from Japan. Few businesses would consider a double-digit increase in cost for a critical component good news. But when that happened to the optics that Leupold sources from Japan, it turned out to be a blessing in disguise.

With no control over the price of optics, the company looked at what they could control the cost of--basically everything else--and began a company-wide process improvement program. Program goal was cost reduction of domestically manufactured components to offset the price increase of their Japanese-sourced lenses.

Leupold has made rifle scopes since the 1940s. Like many shops, it began as a craft-based operation. Processes were centered on the inherent skills of the machinists and other shop personnel.

Going from what was primarily a craftsman mentality to a process-oriented mentality has taken some work. "What we had to do first," says Mr. Owen, "was write down what our people knew. At first some workers felt threatened by the exercise. Soon though, they began to see how written procedures could actually make their jobs easier."

In the old days, if a bolt used in assembly was too long and needed to be cut off, the assembler just did it. Cutting the bolt was considered part of the process for this operation. "Now, with demand for these products increasing, that cut-off may have to be made 100,000 times a year," says Mr. Owen.

"Looking back, it made sense to use a shorter bolt but there was no real mechanism to make that happen. It's tough to identify a process problem when the process is maintained in a person's head," says Mr. Owen.

Now with written procedures in place (Leupold is working toward ISO 9001 certification), the bolt-cutting step can be identified and eliminated by using a proper sized bolt. Many of Leupold's first process improvements were as simple as this example.

Not New Is OK

Leupold is a turning shop. Most of the components needed to make rifle scopes are round or variations of round. During the company's nearly 50 years of making scopes, they've seen and participated in the evolution of turning technology.

Like evolution in nature, evolution in manufacturing is a selection process. Both are based on what works best. In nature, some creatures have changed very little over the eons. Their original design contained enough flexibility to survive environmental changes.

Others were forced to modify their basic design or face extinction. In Leupold's shop, a similar dynamic has been at work. The shop uses 30 single-spindle screw machines. These are mechanicals that crank out rings, dials, collars and other small components that get assembled into a scope.

This older technology succeeds to the degree it adapts to changing manufacturing needs. These machines pass that test. Their inherent flexibility and ability to make parts complete makes them viable for the operation.

Cell Techniques

A scope is mounted to the rifle using two ring mounts. These come in various sizes and configurations to accommodate all of the rifle manufacturers. For example, a Browning takes a different mount than a Remington though the scope itself may be the same for either rifle brand.

Ring mounts are made in pairs. Because these ring mounts come in many sizes, a flexible cell is used to make them. But it's not a cell composed of CNC machine tools. Rather, it's 13 individual manually-operated machines--each set to perform a dedicated operation on the ring mounts.

Blanks are roughed on a screw machine. They then pass through milling and drilling operations and to a precision cut-off operation that halves the ring. This is followed by a drilling and tapping operation so the two halves can be assembled with screws that hold the scope on the rifle.

Because a customer may use one scope on more than one rifle, production of ring mounts usually out-paces production of scopes. Often, several sets of mounts are sold with a single scope.

Before taking a hard look at how these ring mounts were manufactured, Leupold had ten operators working the machine tools now located in this cell. The machines were scattered around the shop. These rings traveled some 1500 feet, winding through the various operations performed.

Using some simple fixturing, parts-handling improvements and more efficient arrangement of machines (putting them in close proximity), these parts now travel approximately 50 feet from start to finish in the cell. Three people operate the entire cell.

Shortening The String

CNC turning was applied early by Leupold in manufacturing the main body of the rifle scope. According to Mr. Owen, the body for the rifle scope traditionally was made from several precision-turned pieces.

The larger diameter is cone-shaped and holds the objective lens, which faces the target. A second turned cylinder is the eye piece, or ocular, end of the scope (the shooter's end of the rifle). These two pieces (objective and ocular lens holders) are threaded into a center turret that was produced on another machine tool. This component holds the wind and elevation adjustments.

It was a multistep process to manufacture these components. They also had to be assembled. Variable dimensions on these bodies are the OD of the objective lens holder and the combined length of both components. Generally, the ocular lens holder is the same diameter for differently sized scopes.

CNC turning was a big improvement for manufacture of these components because of quick changeover from one diameter objective to another. With two variables on the objective end piece and one on the ocular lens holder, CNC allowed Leupold to reduce economical batch sizes and in doing so, lower work-in-process and inventory.

As mill/turn capability in turning centers developed, Leupold saw this as a way not only to increase component throughput but to actually reduce the process steps needed to manufacture the scope body--in effect, shortening the string of processes needed to make the component.

The machine they chose was an Index GSC-65. Its multiprocessing capability and long between-center distance has allowed Leupold to redesign the rifle scope body as a single piece. From a three-machine operation (two lathes and a machining center), this component is now manufactured completely on one machine tool.

The part is cut from an extruded bar that is fed through a 60-mm spindle bore.

Only a change in collet pads is needed to accommodate the various diameters needed for different objective-lens body sizes. A second synchronous spindle picks the work from the main spindle that allows back-turning operations to be performed. The scope body comes off complete. "Not all of Leupold's scope product line has been redesigned for this process improvement--but they will be in time," says Mr. Owen.

No Cop On The Corner

In 1991 Mr. Owen, who is responsible for quality, decided to attack problems of quality at the source. That's when the company began to redeploy the quality personnel and make each workstation responsible for what it produced. The quality functions didn't disappear, but by redeploying the functions, quality became a value-added activity rather than a cost.

Every workstation at Leupold is equipped with the necessary measurement equipment to verify the work being produced. Every operator is responsible for the work coming out of his or her area.

"It's about accountability," says Mr. Owen. "Air gages, granite blocks, height gages--whatever the operator needs--is on hand at each workstation. We have no quality department. We don't consider having the equivalent of a cop on the corner a value-added activity. We hire people to make good components, and we make sure they're trained and have the equipment to do that."

Making The Cut

The different programs for the families of parts produced on the shop's CNC machines and tooling kits are prepared off-line at Leupold. The manufacturing engineering department writes the programs for workpieces at a CAM station and downloads them through DNC to the machine.

Tool offsets are also prepared off-line. A tool presetting gage is linked electronically through DNC to the machine's CNC and all offsets are automatically downloaded to the CNC. "Essentially what the tool setter looks for is to position the cutter around a datum and establish the offset from that," says Mr. Owen. A kit goes out to the shop floor from this presetting area with instruction on placement in the machine--which pocket or turret location number.

All the operator needs to do is call up the program on the machine's CNC, load the tools and start cutting. No time is wasted comping in the machine. This has served to dramatically increase spindle utilization.

Inspection is done at the workstation as parts come off the machine. Corrective action for tolerance drifts is the responsibility of the operator. "When a batch of parts leaves a machining station, they are right," says Mr. Owen.

Window On The Factory

There is no better measurement of the success of a manufacturing operation than the assembly of the various parts that go together to make a product. Whether the product is an automobile or a pocket knife, how the parts fit determines product performance.

It's the same for the rifle scopes that Leupold makes. "Assembly is the window on the factory," says Mr. Owen. "It's there that design, process planning, parts manufacturing and vendor-supplied materials all must come together and work."

All of the improvements made on the manufacturing floor find fruition during the assembly process. If a part that goes into a scope doesn't fit, and the assembler must manipulate it in some way, then expensive time is lost.

Since the beginning of Leupold's efforts to improve process control, the average assembly time for a rifle scope has gone from 4 hours and 10 minutes to 2 hours and 30 minutes. That's significant! Even more important for the company, the cost savings from manufacturing's process improvement have helped offset lens price increases from the currency exchange rate with Japan. This in turn has kept Leupold's scopes price-competitive.

Where From Here?

Once a company gets started down the road of process improvement and installs the basic mechanisms that simplify making procedural changes, a momentum takes over in the shop. This is happening at Leupold.

Equipment is on order to increase efficiency of the ring mount cell. An Emus rotary transfer machine will be installed next year to further automate production of these components. The increase in processing capability will allow Leupold to build these part sets to order--eliminating inventory. It's a big investment but the payoff is an even shorter process string for manufacturing rings and mounts.

New Index machines are also on order. Leupold has received a model G300, and a model ABC is on order and due this fall. These multiprocess CNC machines will reduce the cycle time for a complete, single-piece rifle scope body from 10 minutes to 5 minutes. The additional capacity provided by these machines will allow further changeover of the rifle scope product line from multipiece bodies to single piece.

So the improvements go on at Leupold. "Our ultimate manufacturing goal," says Mr. Owen, "is to manufacture our products to order. We want to get process flexibility to a point where we can respond immediately and efficiently to an order for any of our products, which will allow us to improve our ability to satisfy the customer. We may never get there. But, the point of the exercise and the benefits to be reaped, are in the effort."

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