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Guest Editorial

Reducing rework through technology

By Matthew Chynoweth

FFJ-1014-guest-leadOctober 2014 - Reducing the need for welding rework is a goal of most manufacturers. Rework is often more necessary in automated and robotic welding, though it can be an issue in any sort of welding. If a welded piece can’t pass inspection, it has to be reworked or possibly scrapped. Rework means a skilled manual welder has to grind out the bad weld, make sure the part is still usable, clean and prep the part, and reweld the joint properly. This is time consuming and costly.

In order to reduce those costs, we have to understand what causes the failures. Poor preparation or incorrect weld parameters can cause brittle welds, porosity and incomplete fusion. In automated welding, bad sequencing can mean that welds are missed completely. Rework can also become necessary due to excessive spatter. Spatter causes fit-up problems, clogs equipment and may result in parts that fail to meet specification. These issues can also contribute to necessary rework. 

Ask anyone how to reduce welding rework and many times the answer is, “Do it right the first time.” That’s easy to say and harder to do. Understanding the cause of a failed weld doesn’t always lead to a solution. Proper weld preparation is key to any good weld, manual or automated. Preparing for your specific weld application involves using the correct welding procedure and parameters. Make sure that parts and fit-up are adequate, that surfaces and equipment are clean, and the person performing or overseeing the job is skilled enough to do it right the first time. However, smart choices in equipment and processes also prevent rework.

Modern equipment and welding procedures provide options that eliminate conditions that make rework necessary. A stable arc programmed to your specific application will produce a more consistent weld. An arc that is adaptive with constant high-speed feedback from the torch will produce the most consistent welds. This type of arc and monitoring reduces issues with porosity and penetration by allowing the machine to make minute adjustments to the arc characteristics 

as needed. In certain advanced machines, the wire feed speed can also be adjusted by the machine to ensure the best possible weld. Thanks to high-speed communication between the torch, wire feeder and power supply, these advanced machines can adapt on the fly to handle rework-causing issues such as gaps in part fit-up. This is especially useful in automated situations.

Digital machines can send actual arc values back to a quality-monitoring system. This allows for failed welds to be identified early in the automated process, especially when failures aren’t immediately visible or there is a breakdown in the process as a whole. The process can then be halted and corrected quickly to prevent multiple failed joints and multiple parts requiring rework. Additionally, this information can be stored for review at a later date to analyze the process for overall effectiveness.

Advances in equipment have also led to breakthroughs in reducing spatter and the resulting issues and post-weld clean up. Low-spatter control settings are available on several machines and one system claims zero-spatter, Fronius’ Cold Metal Transfer (CMT). The information regarding CMT states: “The moment the power source detects a short circuit, the welding current drops and the filler wire starts to retract. Exactly one droplet is detached, with no spatter whatsoever. The filler wire then moves forward again and the cycle is repeated.” This is the type of rework-reducing technology available on the market today.

With all of these options, including virtually spatter-free welding and adaptive arc control, the key to reducing rework lies in defining its cause. Once the cause is identified, steps can be taken to allow the system to adjust for sequencing, proper fusion and even part fit-up. Costly rework and downtime can be avoided when the system can adapt within the parameters of the situation at hand. FFJ

Sources

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AIR FILTRATION

IRONWORKERS

NESTING SOFTWARE

SERVICE CENTERS

Camfil APC - Equipment Trilogy Machinery Inc. Metamation Inc. Admiral Steel
Camfil APC - Replacement Filters

LASER TECHNOLOGY

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Alliance Steel
Donaldson Company Inc. AMADA AMERICA, INC. Messer Cutting Systems Inc.

SOFTWARE

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Mazak Optonics Corp.

PLATE

Enmark Systems Inc.
MetalForming Inc. MC Machinery Systems Inc. Peddinghaus Lantek Systems Inc.
RAS Systems LLC Murata Machinery, USA, Inc.

PLATE & ANGLE ROLLS

SecturaSOFT

BEVELING

TRUMPF Inc. Davi Inc. SigmaTEK Systems LLC
Steelmax Tools LLC

LINEAR POSITION SENSORS

Trilogy Machinery Inc. Striker Systems

COIL PROCESSING

MTS Sensors

PRESS BRAKE TOOLING

STAMPING/PRESSES

Bradbury Group

MATERIAL HANDLING

Mate Precision Tooling AIDA-America Corp.
Burghardt + Schmidt Group EMH Crane Rolleri USA Nidec Press & Automation
Butech Bliss Fehr Warehouse Solutions Inc.

PRESS BRAKES

STEEL

Red Bud Industries UFP Industrial AMADA AMERICA, INC. Alliance Steel
Tishken

MEASUREMENT & QUALITY CONTROL

Automec Inc.

TUBE & PIPE

CONVEYOR SYSTEMS

Advanced Gauging Technologies MC Machinery Systems Inc. BLM Group
Mayfran International

METAL FABRICATION MACHINERY

SafanDarley HGG Profiling Equipment Inc.

DEBURRING/FINISHING

Cincinnati Inc.

PUNCHING

Prudential Stainless & Alloys

ARKU

ATI Industrial Automation

LVD Strippit Hougen Manufacturing

WATERJET

Lissmac Corp. Scotchman Industries Inc.

SAWING

Barton International
Osborn Trilogy Machinery Inc. Behringer Saws Inc. Jet Edge Waterjet Systems
SuperMax Tools

METAL FORMING

Cosen Saws Omax Corp.
Timesavers FAGOR Arrasate USA Inc. DoALL Sawing

WELDING

HYDRAULIC PRESSES

MetalForming Inc. HE&M Saw American Weldquip
Beckwood Press Co.

MICROFINISHING TOOLS

Savage Saws Strong Hand Tools
Triform Titan Tool Supply Inc.

 

T. J. Snow Company

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