Welding preparation is an extremely important step when different metal types are joined together for fabrication purposes. For the welding process to be effective, efficient, and accurate on the first pass, it’s crucial to have properly prepared parent materials.
We will take a closer look at surface preparation for welding in more detail.
The Importance of Welding Preparation
When the parent material surfaces are cleaned properly the chances of a strong weld are improved. An operator that understands the best practices for welding preparation can streamline the entire operation and work more efficiently.
What Is Surface Preparation for Welding?
Surface preparation for welding involves the removal of any materials that will impair performance during the initial pass. Including chemicals, contaminants, rust, mill scale, base material coatings, and other impurities.
These materials will prevent proper weld penetration and cause porosity and inclusions. The work surface must be cleaned thoroughly to within an inch of the new weld joint on both sides of the material.
Cleaning stainless steel and alloys with acetone and a wire brush may suffice and it’s a good alternative to more abrasive mediums. All rubber, coatings, paint, rust, powder coat, and other light contaminants can be cleaned with the wire brush.
But if the application does require an abrasive surface clean it’s important to understand what you are trying to remove. For welding preparation, it’s a good idea to start with the less coarse option and increase the cleaning strength as required. Certain heavier coating and mill scale may only be removable with a flap disc or grinding wheel.
Four Best practice approaches that you can use to optimize your preparation for cleaning and grinding.
1. Lower the Grinding Angle
When you clean with a grinding wheel, you can lower the grinding angle to gain maximum control, and this will reduce the gouging risk. The outer corner of a grinding wheel is the usual source of gouging and adopting a steeper approach angle can remove too much surface material on the work piece.
Flattening the angle will widen the surface contact across the grinding wheel and this will make the process less aggressive.
2. Consistent Strokes When Grinding
The grinding stroke should be entered on the pull and not the push. This will improve control and the grinding wheel aggression considerably. Always grind in line with the surface material with smooth and even strokes. This will be effective when you use bonded and coated abrasives.
3. When Grinding Don’t Press Too Hard
When you use wire wheels, it’s important to remember that the wire tips are where the work takes place. So, if you press too hard, it can bend those wires and the tips will not make proper contact with the material.
4. Avoid Arm Grinding
When an operator uses excessive force with their arms only to operate the grinding wheel there are potential problems. The vibrations can take a hard toll on the forearms and wrists, and this can lead to injuries.
To mitigate this risk, it’s a better idea to use the larger muscles in the body and the legs to control and move the grinder. When the entire body is moving in the grinding direction, fatigue is minimized.
The Importance of Welding Preparation-In Summary
Proper surface preparation for welding is the crucial first step when you want to produce high-quality strong welds. Removing the impurities and any coatings from the surface is important. But you don’t want to remove excessive quantities of surface material that can weaken the work-piece (more on this below).
Choosing the correct welding preparation method, tools, and products to clean the surfaces will be critical to help you achieve your desired results.
When too much of the base material is removed or deep gouges and scratches are added to the weld area, this is known as “undercutting”. This result may be included, or the arc control may be degraded during the welding process. This is a real problem if you’re working with stock that has been preworked with a torch or plasma cutting.
Excess slag and plasma dross are usually removed with a chisel or can be ground off with a coarse abrasive product. This may create deep marks on the work-piece surface and any surface impurities can be driven deeper into the material.
This can increase the likelihood of poor coating adhesion and weld porosity at later stages in the fabrication process. These errors can lead to costly rework and loss of efficiency.
Before Welding Four Things You Will Need
There are four essential pieces of safety equipment that you will need before you carry out welding and welding preparation:
- safety glasses,
- welding gloves,
- a fire-resistant jacket,
- an auto-darkening helmet to protect your eyes.
What Is Edge Preparation in Welding?
As the name suggests, edge preparation is the removal of material along the edge of a metal surface that is being prepared for welding. This is only possible with certain types of weld joints.
As an example: The root opening weld preparation is available for the following welds: butt, flare bevel, flare V groove or butt, flare, J groove or butt, U groove or butt, bevel groove or butt, and square groove or butt. But, an angle cut preparation is available, for bevel groove or butt and V groove or butt welds.
What Is the Importance of Edge Preparation?
All edges must be prepared for welding when the assemblies and parts require certain strength levels. To achieve full welding penetration, it’s necessary to cut the metal edges. The welds that the operator creates will replace the material that’s removed. This will make a complete bridge, which will join the two parts together.
The Importance of Welding Preparation- In Conclusion
Welding is a well-understood process and it’s been used in assembly and fabrication for more than a century. Although the materials and techniques are continuously refined to improve efficiency, there are some basic concepts that simply don’t change.
Welding preparation is one of those important stages of welding that can make a real difference. Some operators ignore this stage or use the wrong techniques which degrade the quality of the welds.
The best welds always start with good preparation, and this can be a challenge. A cursory glance at many weld shops will reveal an accumulation of dirt and grime which can contaminate the weld purity. So, it’s important to clean the material in advance and work quickly to ensure that a pure weld is achieved.