June 2008 Edition

WELDING

The Rule of Ones

Implementing Lean Manufacturing concepts and standardizing welding processes let a shop decrease downtime and quality variance

Those in a shop environment know how much downtime accrues from changing a welding cell to accommodate different product runs. For OEM Fabricators Inc., Woodville, WI, downtime cost $2,000 a day, until it adopted the "rule of ones," which standardized its welding processes, and implemented Lean Manufacturing concepts.

OEM is a shop that specializes in fabricating components and assemblies for more than 80 heavy equipment manufacturers across 20 industries, primarily the oil patch, oil exploration, power generation, and crane industries.

Serving that many customers and meeting production runs from one to 250 units per run, welding operators at OEM had to change welding processes, wires, gases, and other variables to accommodate each new product run.

The inefficiencies created by these changeovers, however, didn’t mesh well with the company’s philosophy.

"Our goal is to be an extension of our customers," Scott Exner, manufacturing engineer, said. "We provide the services and products that they choose not to manufacture internally. They need to be able to come to us and receive a quality product, on time, at a fair price."

That’s why the company adopted a "rule of ones" welding system – one process, one gas, one wire, one gun – as part of its implementation of Lean Manufacturing.

With Q-Guns and Centerfire consumables from Bernard, Beecher, IL, OEM reduced its downtime and expanded its welding operation two to three times its size since implementing the welding process standardization. OEM reduced the potential for quality variance between welding operators and greatly reduced the time it took to do initial hiring training for its welders.

Becoming Lean Exposed Flaws

OEM was not experiencing a manufacturing crisis when it began implementing Lean Manufacturing principles in 2004, but as a forward-looking company, it saw the potential offered by becoming Lean.

"Integrating Lean concepts in our operation let us look at all of our processes and how they’re inter-related," Exner said. "We might have as many as 20 people touching a product as it moves through fabrication. Lean principles help us provide our employees with the best information and the best tools to do their jobs."

Providing customers with a consistent and high-quality product has been one of the foundations upon which OEM built its reputation. One of the toughest parts of upholding that reputation was establishing uniformity and consistency among their 115 welding operators while reducing downtime and rework.

Although it took only about 15 minutes for operators to change from welding one product to another, the frequency of changeovers combined with the number of welding stations in the plant totaled a significant amount of time.

"When that changeover is made in a multi-process mode," Exner said, "there has to be a change to a different wire, different gas, and then a re-setup of process parameters. All of that takes time and creates the possibility for inconsistency."

That’s when OEM began investigating the potential to standardize all of its welding operations on a single process, wire, gas, gun, and consumable. The manufacturing flow and improvements and the savings that resulted are part of the reason OEM has been able to increase its size in the short time its two plants have been in full operation.

OEM selected an advanced pulsed MIG process from Miller Electric Mfg. Co., Appleton, WI, that monitors the arc and adapts the current thousands of times per second, letting OEM’s welders pull the trigger and weld while the power source ensures the correct power output.

For the wire and gas, OEM selected a 0.045 ER70S-6 solid wire with a 90/10 argon/CO₂ mixed gas. The high argon content helps produce a stable arc and lets the system produce a spray transfer for high deposition and a calm weld puddle.

The Whole Package

When it came to selecting the one gun and consumables package that would handle almost all of its manufacturing needs, OEM chose Q-Guns with Centerfire consumables from Bernard.

"When we first started integrating Lean principles and standardization into our welding operations, guns and consumables were right at the top of our list," Exner said. "We looked at a lot of packages, but so far nothing has matched the Bernard Q300 gun and Centerfire consumables."

In fact, Exner said he still reviews competitive guns and consumables annually, and he hasn’t found a product with better results for OEM’s applications.

"We brought in guns from other manufacturers and wrote out a comparison listing what we liked and disliked about each gun," he said. "There were some things we liked better on the other guns, but in the end, the Bernard was the whole package."

One of the biggest benefits Exner saw in the Q-Gun was its ability to be custom configured to meet different application needs within the shop. Bernard’s 24-hour online Configurator lets customers build a customized MIG gun by selecting each component, from the contact tip to the power pin, based on specific needs. The Configurator can then be used to request a price quote from the company’s nearest welding distributor.

"Options include different neck lengths, different bends, and others that let it fit into almost any position we need it to get into," Exner said, noting that his operators like the rotatable neck, which lets them access hard-to-reach joints with comfort.

Smooth Transition and Consistent Results

Overcoming operator resistance to change is a constant concern in any manufacturing environment, particularly with regard to equipment that alters the ergonomic environment, such as a welding gun. However, the operators at OEM were accepting of
the Q-Gun.

"I was more reluctant moving to the Q-Gun and Centerfire system than my welders were," Exner said. "My guys loved the curved handles, the weight of the guns, and the different neck configurations, so it was an easy choice for the people using the product to go with Bernard."

Implementing Lean practices resulted in more arc-on time for the operators, but because they were running their guns as high as 260 to 270 amps, Exner became concerned that they would exceed the duty cycle. To date, they have found that the Q300 has been able to handle the company’s welding needs while providing a comfortable weight and maneuverable size that they couldn’t find in a 400-amp gun.

Another factor in OEM’s decision to use Bernard MIG products was the Centerfire consumable system.

"We don’t look at consumables as a big cost item," Exner said. "We look at consumables from a standardization point of view. We’re willing to pay a little more up front for the consumables if they are going to result in improved standardization, increased throughput, and reduced re-work on the back end. That’s what Centerfire provides."

Featuring a fixed-recess, drop-in contact tip that sits in the diffuser and is held into place by a spatter guard in the nozzle, the Centerfire system provides OEM with consistent results, regardless of who is behind the gun, and a calm gas flow that improves weld quality.

Helping to establish uniformity between operators, the Centerfire’s fixed recess contact tip prevents the current and heat variances that occur when operators adjust their contact tips to different depths.

"One of the biggest errors that welders tend to make is in setting the tip recess," Exner said. "That plays a big role in how the arc is going to perform. Two different guys with the same tip recess are going to get results more similar than one guy using different tip recesses."

Exner also was impressed by the gas flow provided by the built-in spatter guard.

"One of the biggest benefits to the Centerfire system was the gas flow," Exner said. "The spatter guard provides a smooth, gentle flow from the nozzle, which does a better job of keeping out the atmosphere. Other consumables create a turbulent gas flow that mixes with the atmosphere because it comes out of the nozzle so fast and uncontrolled."

A Better Product

Standardizing on one brand of consumables also improved OEM’s inventory management system, which reduced downtime and kept its welders more productive.

"Labor is a company’s biggest cost, so we try to eliminate non-value-added time as much as possible," Exner said. "Standardizing on one brand of consumables means that if one operator runs out of tips, he can borrow one from his neighbor, rather than spending time going to the crib trying to track down a tip of the same make and model as he was using."

Although OEM still has a few customers who require a deviation from the rule-of-ones, the majority of customers are satisfied with the results of the philosophy – both in terms of the cost and quality of OEM’s product.

"At a time when most of our suppliers are increasing their prices, our customers are asking for price breaks," Exner said. "Our investment in implementing Lean Manufacturing principles into our welding operations lets us provide our customers with better prices and better products."

Best of all, it has positioned OEM to continue its growth without worry about incorporating new product runs into its existing operations. Bernard

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