Description
Understanding and Extending Contact Tip Life
Contact tip 0.8mm Pkt 10 (5mm x 18mm)
While only a small part of a larger system, contact tips play a critical part in achieving high quality welding performance. The primary function of this consumable is to transfer the welding current to the welding wire as it passes through the centre bore, effectively creating the arc. To achieve the most consistent results, the wire needs to feed through the contact tip with the least amount of resistance possible, while still maintaining electrical contact.
Because of the constant friction from the wire and the exposure to the heat of the arc (and, in some cases, the reflective heat from the base material), contact tips take a tremendous amount of abuse during the course of welding. This abuse can easily turn into contact tip failure without the proper precautions.
Not surprisingly, contact tip failure not only hinders productivity by creating downtime for change over, but it can also negatively affect weld quality and create rework. Adding to that, the cost of replacing contact tips on a frequent basis can add up over time.
Understanding the typical types of contact tip failures and their causes is the best approach to preventing them.
Types of contact tip failure
There are two main types of contact tip failure.
1. Failure that leads to a burnback and its associated problems
2. Failure that produces contact tip wear
Burnbacks occur when a weld forms within the contact tip and can occur at any point along the weld. They are not necessarily the result of poor contact tip performance, but rather burnbacks can result from too slow of wire feed speeds and/or incorrect contact-tip-to-work distance (also referred to as CTWD). The CTWD is the distance between the end of the contact tip and the base material; if the distance is too short (i.e. the contact tip is too close to the workpiece), a burnback can occur. The quality of the wire, incorrect parameter settings and micro-spatter buildup, as well as incorrect wire feeder and liner adjustments can all contribute to burnbacks. When they occur, burnbacks reveal themselves by way of poor arc starts, arc instability, inconsistent wire feeding and, ultimately, stoppages in wire feeding altogether.
Contact tip wear can be both mechanical and electrical. It occurs from the friction of the wire feeding through the bore of the contact tip and is especially prevalent in higher amperage semi-automatic and robotic applications. In the latter, contact tip wear can produce issues with tool center point (TCP), resulting in offset welds and potentially rework, especially in robotic welding systems that do not employ seam tracking. The design of the contact tip and the material it is composed of are two factors that affect a contact tip’s tendency toward wear. Typically, manufacturers use copper for contact tips because it is readily available and offers good electrical and thermal conductivity. Copper, however, has a relatively low resistance to wear, making it more prone to failures. For higher amperage applications, companies often turn to chrome zirconium contact tips due to their strength and their ability to resist wear by heat.
Contact tip 0.8mm Pkt 10 (5mm x 18mm)
Rectifying contact tip failure
All contact tips, regardless of the material used to manufacture them, will eventually fail if used or abused for a long enough periods of time and/or at a high enough temperature. They are, after all, consumables with a finite lifespan. The goal, nonetheless, is to prolong the life of the consumables in order to avoid unnecessary downtime, as well as cost for additional inventory. A good step in achieving those goals is to understand the ways to help prevent contact tip failure.
This Contact Tip is fitted to drapper, clarke, sip mini mig and hobby mig torches etc.
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