The latest restrictions related to concerns about the coronavirus (COVID-19) have made another two large events to be cancelled Welding and Joining Technology by Elmia in Sweden as well as The Industrial Fashion Fair organized by TESS as in Norway.
As safety is always our priority, we fully understand this decision and are looking forward to meeting you at the next editions of these events.
Due to the impact of the novel coronavirus (COVID-19) on the whole society, we want to give a brief update on our actions.
First of all – we work as usual, though in a different way.
Our offices are open, orders are being processed and the production is continuing, so from our Customers‘, Suppliers‘ and Partners‘ perspective nothing has changed. However, considering the safety of our employees, for those who can, we have encouraged them to work from home. For those, who cannot work remotely, we have implemented several precautionary measures in response to the situation. In our proactive work we have, among other things, increased our already high cleaning requirements in our premises. We follow all health and safety recommendations and work actively and regularly to take steps to create a safe environment for our employees.
We have also decided to limit the number of face to face contacts, therefore instead of visits, we will be happy to assist you via phone, skype or video conference. It will allow both you and us to keep in touch and minimize the negative impact of the current situation on the businesses while keeping the safety standards.
Furthermore, we have prepared a contingency plan, specifying the measures to be implemented in the case of a further spread – with direct impact on our business. Moreover, we have appointed a special group that follows daily developments and the guidelines from the authorities.
Keeping in mind our social responsibility, we are doing everything to protect the people – both in terms of health and their economic security.
We thank you for your understanding and assure you that we will do our utmost to limit disruptions this event brings to you and your business.
We will keep you informed if the situation changes.
With DRYPAC® you can rest assured that the electrodes are dry when you need them. They are vacuum packed in factory dry conditions and come in a moisture controlled paper tray. The package is resealable with a new kind of tape that provides extra protection for electrodes left in an opened DRYPAC®. The outer pack is made of corrugated cardboard and the opening on top is easy to fold back, which contributes to easy storage and handling. All DRYPAC® packaging components are of course fully recyclable.
If filler metals become wet or pick up contaminants from the job site, such as dirt, oil, grease, or other impurities, they simply and without question need to be replaced. That replacement leads to three costly problems. One, it causes downtime for changing over the filler metal, particularly welding wires. Two, filler metal damaged by the environment almost always voids most industry-standard one-year warranties on the product. Three, it costs the contractor money—for both the price of the ruined filler metal and for the purchase of new filler metals. These are a trifecta of problems and costs.
Time for Damage Control
When filler metals leave the factory, they are sealed (usually vacuumed, hermetically, and/or placed in a heavy plastic bag or wrap) and in the best possible condition for the job. It’s then the contractor’s responsibility to keep them that way, regardless of the harsh job site conditions. Fortunately, there are some relatively easy steps they can take to help them accomplish this task.
First, contractors should always use gloves when handling filler metals. Solid wire, in particular, can easily pick up sweat from bare hands. This moisture causes rust to form on the surface of the wire, which in turn leads to poor wire feeding and may create porosity in the finished welds. Contractors can usually tell through a visual inspection of solid wire if it’s been damaged in this way: the rust mark will often be in the exact shape of a handprint! Other types of filler metals won’t show such telltale signs of improper handling, but it is nonetheless important to wear gloves when removing them from their original packaging or preparing them for welding.
Because plasma and oxy-fuel cutting create a significant amount of dust, these processes, which are both common on the job site, should be kept clear of filler metals. The cutting dust can accumulate on the surface of flux-cored and solid wires, and cause poor wire feeding. Cutting dust can also clog the contact tip and nozzle in these applications, creating poor electrical conductivity and an unstable or erratic arc. In a stick electrode application, dust can lead to weld porosity. For all of the aforementioned reasons, it is a good practice to keep cutting activities in a separate area from where welding occurs.
Contractors should also keep filler metals away from water, oil, grease or other similarly damaging elements. These contaminants can all lead to poor weld quality, rework and/or welding performance issues that negatively affect productivity on the job site. Moisture, especially, can cause hydrogen-induced cracking that must be repaired.
The single most important practice a contractor can implement on a job site, however, is to properly store filler metals when they are not in use. First, when flux-cored welding or MIG welding with solid wire, contractors should cover the welding wire spool with a plastic bag if they plan to leave it on the wire feeder overnight. That is the least they should do.
A better practice involves a few more steps but it is worthwhile to avoid potential welding wire contamination. At the end of the workday, remove the spool from the wire feeder, place it in a clean plastic bag and close it securely. Then place the secured package into the original box and store it in a clean dry area until it is ready for use again.
As a side note, using an enclosed wire feeder, when possible, is also a good way to protect flux-cored wire and solid wire from harsh job site environments. Still this type of feeder will not prevent damage to the filler metal surface if the welding wire is left in the enclosed feeder for any length of time. Contractors should still follow proper handling storage procedures.
Stick electrodes also require proper handling and storage on the job site if contractors are to achieve proper weld quality, maintain compliance with the specified welding parameters and eliminate unnecessary downtime.
Without question, moisture is the number one enemy of stick electrodes—it can cause hydrogen induced-cracking, porosity and a host of other weld discontinuities that require rework. Depending on the type, stick electrodes must often be stored in a holding oven at a specific temperature (See Figure 1 above) to protect them from moisture. In some cases, a specific welding procedure or code even dictates how long a package of stick electrodes can remain open before it must be discarded—regardless of whether it has been stored in an oven or not.
Not surprisingly, leaving a package (can or carton) of stick electrodes open and/or storing it improperly during or after the workday are the biggest mistakes contractors can make on the job site, especially with low-hydrogen products. Contractors should always follow the welding code specifications for the job, as well as the filler metal manufacturer’s instructions for the particular stick electrode. Proper oven storage or holding temperatures are key. Contractors should also look for packaging options that provide greater moisture resistance, such as vacuum pack DRYPAC® or hermetically-sealed metal can, and always close the package after retrieving an electrode.
In the event that stick electrodes have been exposed to moisture, contractors should follow the recommended procedure for reconditioning them. Reconditioning involves placing the damaged electrodes in an oven at a given temperature for a specified period of time. Instructions for reconditioning are included with the original stick electrode package, or can be determined by contacting a trusted welding supply distributor.
Note welding wires should never be reconditioned.
A Small Price to Pay
Most contractors would likely agree that filler metals are only one of many concerns they have on a job site. Worker safety, compliance to the job specifications, material handling, and other job site issues certainly take precedence. Still, the goal of any job is to complete it correctly, on time, under budget, and with the greatest amount of efficiency. Properly handling and storing filler meals can be a simple way to help make such goals a reality. It just takes a little time and know-how to yield positive results—both in cost savings and productivity.
Article based on ITW Welding global experience and knowledge.
Mistake No. 1: Improper Filler Metal Storage and Handling
Storing filler metals in an area where they are prone to accumulating moisture or exposed to other contaminants (e.g., dirt, oil or grease) can have an adverse effect on their welding performance. To prevent damage, companies should store filler metals in a dry, clean area with a relatively constant temperature until they are ready for use. Spools and coils of wire that are kept on the wire feeder for an extended period should be covered securely with a plastic bag or removed from the wire feeder and stored in the original packaging. An enclosed wire feeder can also protect against contaminants. Such precautions prevent damage that can lead to poor weld quality, and ultimately, rework.
Mistake No. 2: Repurposing Old Equipment
It is important for companies to use the best equipment for the job. Repurposing old or dilapidated power sources, welder/generators or wire feeders can cause quality issues, not to mention downtime and additional costs for troubleshooting problems that inevitably arise from using dated equipment and technology. Instead, companies should consider the newer technologies available in the marketplace, recognizing the advantages these can offer in terms of improving weld quality and productivity. In most cases, newer equipment can provide companies with a quick return on investment and greater long-term savings – in a relatively short payback period. Newer technologies often offer benefits like improved power efficiency, better deposition rates, lower weld prep time and faster training, all of which ultimately add up to greater arc-on time and productivity. Performing a thorough cost-savings analysis before buying new equipment can help companies assess their potential return on investment, as well as justify the capital expenditure.
Mistake No. 3: Using the Wrong Size MIG Gun
Using a too-low or too-high amperage MIG gun can lead to unnecessary costs for purchasing and replacing this equipment. Welding operators rarely spend the entire day welding or welding continuously, as there is downtime for part preparation, movement and/or fixturing. For that reason, it may be possible to use a lower amperage MIG gun or one with a lesser duty cycle on some applications. For example, using a lighter and smaller 300-amp MIG gun instead of a 400-amp model can provide welding operators with greater maneuverability and reduce downtime for fatigue. Lower amperage MIG guns tend to cost less, as well. Conversely, on higher amperage applications and/or those that require longer periods of welding, it is important to use a higher amperage gun. Skimping and purchasing a lower amperage MIG gun in this situation can lead to overheating, premature failure and greater long-term costs. Companies should consult with a trusted welding distributor for MIG gun recommendations for their application.
Mistake No. 4: Improper Preheat or Interpass Temperature Control
It is not uncommon for companies to preheat too little or skip this portion of the weld procedure altogether. Yet preheating is one of the biggest deterrents against cracking, as it slows down the cooling rate after welding. The type and thickness of the material being welded will determine preheat and interpass temperature. These requirements can be found in the application’s welding procedure, welding codes or other fabrication documents. For the best results, welding operators need to preheat the material completely through and extend the heated area to approximately 8 cm on either side of the weld joint. Welding should commence while the material is at or above the preheat temperature. Allowing the weldment to cool below the required interpass temperature may also lead to cracking.
Mistake No. 5: Ignoring Preventive Maintenance
Preventive maintenance (PM) is a frequently overlooked part of the welding operation, but it is critical to preventing unscheduled downtime and keeping repair costs low. A well-performed PM program can also help increase productivity, extend equipment life and create a workplace philosophy that encourages shared responsibility for, and interest in, preserving the integrity of the welding equipment. Companies should develop a regular timetable to inspect their power sources, wire feeders and MIG gun or TIG torches during scheduled downtime in production. Between welding shifts is often enough time to perform routine inspections. Checking consumables regularly for spatter build-up — and replacing these components as needed — is also an important part of a viable PM program.
Mistake No. 6: Shielding Gas Inconsistencies
Using the correct type and/or mixture of shielding gas can help companies prevent weld defects, minimize excessive spatter and reduce costs for rework or post-weld cleanup. Shielding gases also determine arc characteristics and weld penetration on a given application. Straight CO2 provides good weld penetration, but it is prone to spatter and has a less stable arc than mixtures that include argon. High argon mixtures (a minimum of 85 percent argon for solid wire or as low as 75 percent for metal-cored wires) are the best choice. These mixtures can be used in the spray transfer process to promote higher deposition rates and generate less spatter. For TIG welding, the appropriate argon/helium mixture can improve speed, quality and arc characteristics. For both MIG and TIG welding operations, companies should purchase their shielding gas from a reputable welding distributor and be certain that it meets the purity requirements for their application. All gas delivery systems should be free of contaminants that could enter the weld puddle and welding operators should use the correct shielding gas flow rate. Too little gas flow won’t properly shield the molten weld pool, while too much flow can cause turbulence and aspirate air into the weld puddle. Protecting the weld puddle from drafts is also critical.
Mistake No. 7: Purchasing Filler Metals Based on Cost Only
Due to the initial up-front cost savings, the temptation may be great for companies to purchase less expensive filler metals. However, doing so can often lead to greater long-term costs and lower productivity levels. It is not uncommon, for example, to experience downtime associated with poor wire feeding, excessive spatter or, potentially, weld defects when using lower quality filler metals. Companies may also find themselves experiencing an excessive amount of time for non-value-added activities (those that do not directly contribute to their throughput), such as applying anti-spatter and post-weld grinding or rework. For that reason, it is important to look at the total cost of using particular filler metals, as opposed to the per-unit cost. If more expensive, higher quality filler metals can minimize labor costs for non-value-added activities and provide better weld quality and/or greater productivity, then the higher up-front cost makes good sense in the long run.
Mistake No. 8: Improper Weld Preparation
Skipping steps in weld preparation can lead to weld defects, rework or scrapped parts. Welding operators should always take care to clean the base material before welding to prevent contaminants like dirt, oil or grease from entering the weld puddle. Similarly, monitoring part fit-up is a critical part of the pre-weld process. Welding operators should carefully assess the weld joints to ensure there are no excessive gaps, as poor part fit-up can lead to issues like burn-through or distortion on all materials, but particularly when welding on materials like aluminum or stainless steel. Clamping or fixturing a part in the correct position is also a good practice to help protect materials like stainless steel against distortion or buckling.
Mistake No. 9: Disregarding MIG Gun Consumables
It is not uncommon for companies to overlook the importance of their MIG gun consumables. Unfortunately that oversight can lead to a host of problems, including unscheduled downtime for changeover and/or rework of weld defects caused by a poorly performing contact tip, nozzle or liner. Welding operators should always select the appropriate style of nozzle for their application to ensure good shielding gas coverage, properly trim and install their liners according to the manufacturer’s recommendations, and select a contact tip that corresponds appropriately with their welding wire diameter. As with filler metals, companies should also avoid the temptation to purchase less expensive, lower quality consumables. These typically do not last as long or perform as well as OEM products, leading to more downtime and greater costs to purchase replacements and change over consumables.
Mistake No. 10: Overlooking Training Opportunities
As with other parts of the welding operation, investing time and money in training can yield significant long-term benefits for companies. Not only do welding operators benefit individually from process and equipment training, but in many cases it can also help them optimize the welding operation for greater efficiency. Too, proper training can give companies a competitive edge over those who have less-skilled labor and it promotes greater teamwork among employees. Typically, training opportunities are available through equipment and filler metal manufacturers or through welding distributors. In some cases, working with a local technical college can lead to training for specific applications and markets, allowing companies to bring in welding operators who are already trained for a given application and better promote their position in a given industry.
Making mistakes is human nature, but with some careful consideration, it is easy to avoid some of the more common ones associated with running a welding operation. Measuring out long-term savings, versus cutting costs up front, is a particularly good way to avoid pitfalls that could lead to excessive downtime, quality issues or lost productivity. And it can have an excellent impact on a company’s bottom line.
Article based on ITW Welding global experience and knowledge.
Metal-cored wires have a different structure and composition than solid wires, which results in distinctive operating characteristics, too. The wires consist of a hollow metal sheath into which filler metal manufacturers deposit metallic powders and/or alloys, including iron, that are designed to provide characteristics ranging from arc stabilization to higher tensile strengths and more. As a result of this tubular structure, metal-cored wires carry the welding current though the outside metal sheath to the work piece instead of through the entire cross section as with solid wires. At equivalent amperage settings, metal-cored wires also carry higher current densities. The result of both factors is a broad, cone-shaped arc and a wide penetration profile, as well as high burn-off rates that increase deposition rates and can provide faster travel speeds.
Metal-cored wires operate using the „spray transfer“ mode of droplet transfer with high argon shielding gas mixtures (a minimum of 75 percent argon is recommended). Using a constant voltage (CV) power source, the wires are capable of flat, horizontal, vertical-down and overhead welding and can also be used for vertical-up welding, but require a pulsing-capable power source to do so or must be adjusted to the short-circuit mode using a CV power source. Generally speaking, the wires operate at a lower deposition rate in the vertical-up position than flux-cored wires, and at about the same deposition rate as solid wire in the vertical-up position.
Typically, metal-cored wires are available in diameters ranging from 1.0 mm to 1.6 mm.
Identifying the Applications
Like any filler metal, metal-cored wires have applications for which they are better suited than others. They are appropriate for welding on mild, low-alloy and stainless steel, but are not recommended for welding sheet metal. Metal-cored wires work particularly well in the automotive industry for welding components such as chassis and steel wheels, primarily due to their ability to provide a wide bead profile and higher travel speeds. In the manufacturing and fabrication industries, metal-cored wires are well-suited for welding agricultural and heavy equipment, as well as rail cars, mostly due to their ability to weld through rust and mill scale (the fine oxide layer found on hot-rolled steels) — both common factors encountered in these applications. The wires can also aptly weld on 6 mm and thicker plate found in agricultural and heavy equipment manufacturing applications, and are usable for applications in the food and chemical industry, which, conversely, tend to be composed of thinner materials.
In addition, metal-cored wires can often be used as an alternative on certain applications currently using the submerged arc or gas-shielded flux-cored welding processes, as well as on many of the same applications that employ solid wire. These include solid wire applications requiring single-pass welding for welds that are 7 cm or longer, and those applications welded in the flat and horizontal position using the spray transfer mode. On such solid wire applications, companies who choose to convert to metal-cored wires can often increase the wire diameter by one size over a solid wire. Doing so often lets them standardize on a single wire diameter within their facility and allows for welding on a variety of joint sizes and material thicknesses.
Metal-cored wires are typically not recommended for applications requiring a lot of out-of-position welding, but they are good for single- and multi-pass welding using a robotic or automatic welding process. Other applications where metal-cored wires can be used include welding piping or other components where poor fit-up occurs, applications prone to burn-through and those requiring aesthetic bead appearances.
The Attributes and What They Mean
When used with the correct shielding gas mixtures (see previous section) and welding parameters (these are dependent on the application), metal-cored wires provide good weld penetration and high deposition rates, as well as fast travel speeds. Because of the way that these wires carry the welding current and burn off, they create very little spatter, as well as low amounts of slag, and offer very good gap bridging. Certain metal-cored wires offer chemical composition that helps minimize silicon deposits at the toes of the weld, while others are formulated to provide a specific chemistry and/or to increase tensile or impact strengths. Most are very capable of minimizing instances of porosity and providing good sidewall fusion to reduce instances of undercut in the final weldment and rework on defective parts.
On average, metal-cored wires cost more per kg than other filler metals, particularly solid wire. Many companies, however, still select this type of filler metal because of its potential for reducing costs in other areas of the welding operation, particularly in the pre- and post-weld areas. Often the pre-weld areas of a welding operation are used for activities like grinding, sandblasting or degreasing materials in preparation for moving them to the weld cell. In many cases, metal-cored wires can eliminate the need for these activities prior to welding because they can weld through mill scale and rust and they create little spatter. The lack of spatter means companies may be able to eliminate the need (and cost) of using anti-spatter and they can often take welded parts directly for painting without needing a separate cleaning operation beforehand. In certain cases, the elimination of such pre- or post-weld activities can allow companies to reallocate labor elsewhere in the welding operation.
In the welding cell, the fast travel speeds and high deposition rates that metal-cored wires provide can frequently increase productivity, as well. That improvement is most often seen in robotic and automatic welding applications.
What Else Is There to Know?
Metal-cored wire isn’t for every application. In certain ones, however, it can provide the welding performance a company wants and needs. For companies who are considering implementing this technology, it helps to assess the current welding operation and identify whether there are bottlenecks in productivity that exist due to pre- or post-weld activities like grinding or if there are quality issues, such as lack of fusion, spatter or undercut. In some cases, metal-cored wire can help eliminate these problems and improve the efficiency of the welding operation in the process.
Article based on ITW Welding global experience and knowledge.
Diese Website verwendet Cookies und andere Tracking-Technologien, um Ihnen unsere Dienste zur Verfügung zu stellen, Ihr Browsing-Erlebnis zu verbessern, die Leistung und Funktionalität unserer Dienste zu erhöhen, unseren Website-Verkehr zu analysieren und zu verstehen, woher unsere Besucher geografisch kommen. Sie können die Verwendung von Cookies über die Einstellungen Ihres Webbrowsers steuern. Cookie-Hinweis DatenschutzhinweisErlaube alle Cookies