Manufacturing Expertise

Welding is not a commodity. The same joint design welded by two different shops, with different process controls, filler selection, and inspection discipline, can produce results that look identical and perform very differently under load, fatigue, or corrosion. For engineering teams sourcing welding services for prototype or production parts, understanding what separates a capable welding operation from an average one is what separates a successful build from an expensive redo.

This guide covers the welding processes used in custom fabrication, material-process pairing, what to expect from prototype versus production welding, and how to evaluate a welding partner before you hand over drawings.

For context on how welding fits into the broader fabrication workflow, see our complete guide to custom metal fabrication.

What Are Custom Welding Services?

Custom welding services are welding operations performed to a specific engineering design, not off-the-shelf product assembly. This includes prototype weldments, small batch production welding, structural weld-fabricated assemblies, repair welding, and build-to-print welding of complete assemblies.

The “custom” distinction matters because it implies working from engineering drawings with specific joint types, weld sizes, material grades, and inspection requirements, rather than following a fixed production routine on standard parts. Custom welding services require welders who can read drawings, interpret weld symbols, select appropriate procedures, and hit dimensional callouts across a variety of part geometries.

MIG vs. TIG Welding: Which Process Is Right for Your Parts?

MIG and TIG handle the majority of custom welding work. The right choice depends on material, thickness, joint geometry, required weld quality, and production volume.

MIG Welding (GMAW)

MIG welding feeds a consumable wire electrode continuously through the welding gun and uses a shielding gas to protect the weld pool from atmospheric contamination. It is faster than TIG, easier to run on thicker sections, and suitable for higher-deposition applications. MIG is the first choice for structural carbon steel fabrication, heavier plate welding, and production applications where throughput matters.

Limitations: MIG produces more spatter than TIG and is less suitable for out-of-position welding on thin material. It is generally not the preferred process for aluminum sheet or precision stainless applications where weld appearance and heat control are critical.

TIG Welding (GTAW)

TIG welding uses a non-consumable tungsten electrode with a separate filler rod added by hand. The welder has precise control over heat input, filler deposition, and weld pool, producing cleaner, more consistent welds with a better cosmetic profile. TIG is the preferred process for aluminum, stainless steel, thin-gauge material, and any application where weld quality, appearance, or corrosion performance is a specification requirement.

Limitations: TIG is significantly slower than MIG and requires higher welder skill. For heavy structural applications where speed and penetration are the priorities, MIG is more economical.

Stick Welding (SMAW) and Flux-Core (FCAW)

Stick welding is used for field repair, heavy structural work, and applications where shielding gas is not practical. Flux-core provides higher deposition rates than MIG on thick material and works in outdoor environments. Neither is commonly used in precision custom fabrication shops for engineered parts, though both have valid structural applications.

Welding Aluminum, Stainless Steel, and Carbon Steel

Aluminum Welding

Aluminum welding requires TIG with AC current. Alternating current is required to break the aluminum oxide layer that forms instantly on the surface and is more refractory than the base aluminum. Filler selection follows AWS D1.2 aluminum welding standards: 4043 filler for general-purpose aluminum welding and crack-sensitive applications; 5356 for higher-strength joints and applications requiring anodizing after welding.

Common aluminum welding challenges: burn-through on thin sections (aluminum conducts heat rapidly, leaving little time to react), porosity from contamination (aluminum is highly sensitive to moisture, oil, and oxide contamination), and heat-affected zone softening on 6061-T6, which loses temper in the HAZ and cannot be restored without full heat treatment.

At Bravo Team, aluminum welding covers 5052, 6061, and 6063 alloys using TIG for precision prototype work and production assemblies.

Stainless Steel Welding

Stainless steel welding requires attention to heat input and shielding. Sensitization, chromium carbide precipitation at grain boundaries in the heat-affected zone, reduces corrosion resistance if heat input is excessive or cooling is too slow. Proper filler selection (308L for 304 base, 316L for 316 base), appropriate heat input, and back-purging on tubing and pipe applications preserve corrosion resistance at the weld joint.

TIG is the standard process for precision stainless work. MIG with short-circuit transfer (STT) is used for higher-volume stainless production where appearance is secondary.

Carbon Steel Welding

Carbon steel welding is the most common fabrication welding application. MIG (ER70S-6 wire) handles the majority of structural carbon steel work. Preheat is required on plate above 1″ thickness and higher-carbon grades to prevent hydrogen cracking in the HAZ. Post-weld heat treatment (PWHT) for stress relief is specified on some structural applications and pressure-containing components.

Welding Services for Prototype Parts

Prototype welding places different demands on a welding operation than production welding. Quantities are small, often one or two units. Drawings may be incomplete or evolving. The welder needs to interpret intent, flag potential issues, and execute to the drawing without a production routing to follow.

Effective prototype welding services include:

• Drawing review before welding begins, catching weld access issues, joint design problems, or missing callouts before they affect the part
• Flexibility on sequencing when drawings change during the build
• Communication back to the engineering team on what was found and what was done
• First-article documentation when dimensions are critical

The most valuable thing a prototype welding partner brings is not just welding skill, it is the judgment to recognize when something does not look right and the communication discipline to surface it before it becomes a problem.

That judgment is built through experience. It is exactly what Bravo Team brings to every welding partnership: 112 years of collective machining and fabrication experience, applied from the first tack weld to final inspection.

Small Batch Welding and Build-to-Print Production

Custom welding services for small batch manufacturing and build-to-print fabrication require a different operational model than high-volume production welding. There is no dedicated tooling, no established routing, and no experienced crew that has run this part a hundred times.

What makes small batch welding work: fixturing that is flexible enough to accommodate part-to-part variation, welders who read drawings rather than following memory, and in-process inspection that catches dimensional drift before it compounds across a batch.

At Bravo Team, our fabrication shop operates as a high-mix, low-volume environment by design. Our welders and fabricators are equipped for the breadth of work that comes with prototype and small production welding, not optimized for a single repeating job.

Case Study: Rapid-Turnaround Frame Fabrication and Welded Assembly

A fast-service restaurant automation program needed a structural aluminum frame delivered on a compressed timeline. The frame housed two linear-motion stage pairs for an automated food-prep machine, precision alignment of the stages to the frame was critical.

Bravo Team’s scope included full material procurement, custom machining of 6061 aluminum brackets and sensor mounts to exact tolerances, assembly of the linear stages onto the finished frame, and delivery of a ready-to-integrate unit. Frame geometry evolved multiple times in the two weeks before build start. Every revision was absorbed without a schedule slip.

From first request to delivered, assembled frame: seven weeks.

“The ability for us to move at the pace we do really saves our clients time and money. We’re moving at speeds that most people can’t move.”   Rich Neal, Director of Manufacturing, Bravo Team

Weld Joint Design for Custom Parts

The geometry of a weld joint affects strength, access for welding, inspection access, and cost. Joint design is an engineering decision that belongs in the drawing stage, not something left to the welder to determine at fit-up.

• Fillet welds: The most common weld type in custom fabrication. Applied to T-joints and corner joints. Size is specified by throat or leg dimension. Fillet welds do not develop the full strength of the base material but are sufficient for the majority of structural applications when properly sized and inspected.
• Full-penetration groove welds (CJP): The weld penetrates the full thickness of the base material. Required when the weld joint must develop the full tensile strength of the member, moment connections, pressure-containing joints, and high-fatigue applications. Requires joint preparation (bevel or J-groove) and typically backing or back-gouging.
• Partial-penetration groove welds (PJP): Penetration partway through the member thickness. Used when full-penetration is not required but fillet weld geometry is not applicable. Less common in custom fabrication than fillet or CJP.
• Plug and slot welds: Fill a hole in the overlapping member to join it to the member below. Used when fillet or groove welds are not accessible. Less common in structural applications but useful in sheet metal assemblies.

Joint access is as important as joint type. A weld that can be reached with a standard gun in flat position is faster, more consistent, and easier to inspect than a weld in a restricted overhead or vertical position. Reviewing joint access before fabrication begins, while the drawing can still be changed, prevents restricted-position welds that add cost and quality risk.

How to Evaluate Weld Quality on Incoming Parts

Receiving inspections for welded parts require more than a visual check. Understanding what to look for, and what acceptance criteria apply, is part of qualifying a welding fabrication partner.

• Weld size and length: Fillet weld leg size and weld length must match the drawing callout. Undersized welds are common when welding is rushed. Measure with a fillet weld gauge, not by eye.
• Weld profile: Excessive convexity (overfill) creates stress concentration at the weld toe. Underfill reduces throat dimension below the specified size. AWS D1.1 specifies acceptable weld profile limits.
• Porosity: Gas pockets in the weld metal appear as round surface indications. Scattered porosity may be acceptable per code; linear porosity or large gas pockets typically are not. Check AWS acceptance criteria for the applicable standard.
• Undercut: A groove melted into the base material adjacent to the weld toe. Reduces base metal cross-section and creates a stress concentration. AWS D1.1 limits undercut depth by application.
• Cracks: Any crack in a structural weld is a reject, no exceptions. Cracks in the weld or heat-affected zone require removal and rewelding. Hot cracking (solidification cracking) and cold cracking (hydrogen-induced) have different root causes and different corrective actions.

Welding and Fabrication Services: What to Include in Your RFQ

A well-structured RFQ for welding services gives the fabrication partner what they need to quote accurately and execute correctly: complete engineering drawings with weld symbols and material callouts, inspection requirements and applicable standards, finish specification, required delivery date, and quantity. Requests for quote based on descriptions or rough sketches produce estimates with wide variance. The tighter your package, the tighter the quote, and the less ambiguity during production.

Frequently Asked Questions About Welding Services

What is the difference between MIG and TIG welding?

MIG welding uses a continuously fed wire electrode with shielding gas, producing faster, higher-deposition welds suited for structural carbon steel and production applications. TIG uses a non-consumable tungsten electrode with a hand-fed filler rod, producing cleaner, more precise welds with better heat control, the preferred process for aluminum, stainless steel, and precision applications.

Does welding melt the metal?

Yes, welding melts the base metal at the joint and fuses it with a filler material (or in autogenous welds, fuses the base metal to itself). The weld pool is molten metal that solidifies as it cools. The heat-affected zone (HAZ) around the weld pool is not melted but is heated enough to alter the metal’s microstructure and, in some alloys, its mechanical properties.

What are custom welding services used for?

Custom welding services produce prototype weldments, structural assemblies, machine frames, equipment brackets, repair welds, and build-to-print fabrications from engineering drawings. They differ from production welding in that each job is specific, requiring the welder to interpret drawings, select procedures, and execute to specified quality standards without a fixed production routine.

What welding process is best for aluminum?

TIG welding with AC current is the standard process for aluminum. It provides the arc cleaning action needed to break the aluminum oxide layer, precise heat control to manage burn-through on thin sections, and clean weld quality suitable for anodizing. MIG with ER4043 or ER5356 wire (pulsed MIG) is used for higher-volume aluminum welding where TIG speed is a constraint.

Welding Services for Prototype and Production, Built In-House

Bravo Team’s welding and fabrication team covers MIG and TIG welding across aluminum, carbon steel, and stainless steel in our in-house fabrication shop. Our welders work directly alongside engineers and machinists, which means prototype revisions, fit-up questions, and DFM feedback happen in real time.

If you have a welding or fabrication project ready to move, talk to a machinist today.