GMAW lassen van aluminium: Een uitgebreide handleiding

Pre-welding Preparation

Preparation of Materials

It is crucial to prepare materials properly for GMAW to ensure high-quality welding, especially when using aluminum, because it is highly reactive to contaminants.

Reinigen en ontvetten

Before welding, aluminum surfaces should be cleaned to remove any oxide and contaminants such as oil or dirt. To avoid contamination, use a stainless-steel wire brush designed specifically for aluminum. After brushing the surface, use a solvent such as acetone or an aluminum cleaner to remove any remaining grease.

Aligning and clamping

Align the pieces exactly after cleaning. Clamps can be used to secure the material during the welding process. It prevents the material from warping or moving due to heat. This ensures a cleaner, more accurate joint.

Machine instellen

For GMAW to work on aluminum, you must set up your machine correctly.

Configuring Voltage & Wire Speed

The thickness of aluminum and the type of wire are essential factors in determining the correct settings. Aluminum requires higher voltage and wire feed speeds than steel. Start with the manufacturer’s recommended settings and then adjust accordingly.

Test Runs and Adjustments

Test your project on scraps of the same thickness and material. You can then fine-tune your voltage and wire speed. Adjust the settings until you get good penetration and a bead that is clean without excessive spatter.

GMAW Aluminum Welding Techniques

Basic Welding for Aluminum

It is essential to master the basic techniques of GMAW to achieve firm and visually pleasing welds.

Push vs. Pull Techniques

Pushing is more often preferred to pulling when welding aluminum. The torch can be pushed away from the weld pool to improve visibility, reduce slag accumulation, and provide cleaner gas coverage. This technique produces cleaner, smoother welds that are less porous.

Angle and Speed of welding

Keep a constant angle of 10 to 15 degrees tilted in the direction of travel. This angle allows for better heat and gas distribution. The welding speed should be high enough to prevent overheating of aluminum but low enough to allow for adequate filler metal and fusion.

Advanced Techniques

As your projects change, and primarily as you work with thicker pieces of aluminum, advanced GMAW skills become more critical.

Dealing with Thicker Materials

Consider using a mixture of argon, helium, and power settings to create thicker aluminum. It is also beneficial to pre-heat the metal to reduce the cracking risk and manage heat dissipation.

How to Reverse Warpage and Distortion

Use backstep and intermittent welding techniques to minimize distortion and warpage. These methods allow for the cooling of the material between welds and control the heat input. They maintain structural integrity and alignment.

Veelvoorkomende problemen oplossen

GMAW aluminum problems can be solved with a few simple adjustments.

Preventing Burn Through

Use a lower voltage, a faster wire feed, and a higher travel speed to prevent burn-through. These adjustments reduce the amount of melting and manage heat input.

Spatter and Porosity Management

Reduce spatter with a finely tuned gas flow. Also, make sure the wire feed rate matches the welding current. For a porosity-free weld, ensure the material is dry and clean before welding. Also, the shielding flow must be adjusted to achieve adequate coverage.

After-Welding Practices

Koeling en reiniging

It is essential to let the aluminum cool down properly after welding. Avoid rapid cooling methods such as compressed air or water, which can cause stress and cracking. Let the piece cool in ambient air. Remove any slag with a wire brush and clean any spatter, oxidation, or slag that may have formed while welding.

Methods of Inspection and Testing

It is essential to ensure the integrity and quality of your welds, mainly when they are used in critical applications. Post-welding procedures include regular inspections and tests.

Visual Inspections

Start by performing a visual inspection of the area surrounding the weld. You can easily detect discontinuities like cracks, undercuts, or incomplete fusion. A uniform, smooth bead indicates a good weld.

Non-destructive Testing Techniques

Non-destructive tests (NDT) can be used for a more detailed analysis. Common techniques include:

• Ultrasoon testen: High-frequency sound waves detect defects beneath the surface weld. This method can be used to identify internal cracks and porosity.
• Radiographic Test (RT): Uses X-rays and gamma radiation to create images of a weld. This technique is excellent for visualizing the internal structures of welds and detecting defects.
• Eddy current testing: Uses electromagnetic induction for surface and near-surface defects. This method is beneficial for thin material.