The ER70S-6 .045-inch MIG welding wire is a solid, copper-coated mild steel wire sold on a 44 lb spool, aimed at shops that run a lot of wire through heavier steel. The .045 in diameter suits thicker material and higher amperage than the common .030 and .035 in sizes, and a 44 lb spool only makes sense if your wire feeder can mount it. This review covers what the wire is for, what to check before buying, and who should choose a smaller diameter or spool. It is based on the Amazon listing and standard AWS classification knowledge, not hands-on testing.
Quick Verdict
Best For: Fabricators and repair shops welding medium to heavy mild steel with a MIG machine that takes .045 in wire and a 44 lb spool.
Bottom Line: A 44 lb spool of .045 in ER70S-6 is a production-size purchase. It is a good fit for heavy fabrication with a feeder built for it, and a poor fit for thin sheet metal or small hobby machines. Check the spool dimensions and your feeder before you order.
| Specification (per the listing) | Detail |
|---|---|
| Product type | Solid MIG welding wire |
| Classification | ER70S-6 (per the listing) |
| Wire diameter | .045 in (about 1.1 mm) |
| Spool weight | 44 lb (per the listing) |
| Finish | Copper-plated (per the listing) |
| Winding | Layer wound (per the listing) |
| Paperwork | The listing says a material certification is included; confirm before ordering if you need it |
| Typical use | Mild steel fabrication, structural steel, steel with some mill scale |
| Not for | Aluminum, stainless steel, thin sheet metal, or gasless welding |
What Is ER70S-6 .045-Inch MIG Welding Wire?
ER70S-6 is a solid carbon steel wire with extra manganese and silicon. Those deoxidizers help the puddle wet in and tolerate light mill scale, which is why it is the common choice for general mild steel MIG welding. The .045 in diameter moves more metal per minute than .035 in wire, so it suits thicker joints and higher amperage.
It still needs shielding gas. A 75 percent argon, 25 percent CO2 mix is common for mild steel, and 100 percent CO2 is also used. Follow your welder chart for voltage and wire speed.
Before You Buy: A 44 lb spool is large and heavy. Check the spool diameter, width and arbor hole on the listing against your feeder and spindle, and confirm that your machine is rated for .045 in wire.
When .045 in Wire Makes Sense
- Steel plate and structural members roughly 3/16 in and thicker, where you need deposition rate.
- Multi-pass welds on heavy sections.
- Shops that use enough wire to finish a large spool before it rusts.
It is a poor choice for thin sheet metal, where the extra heat can burn through. For auto body and light fabrication, .023 to .030 in wire is usually easier to control.
Machine Fit Checklist
- Wire size range: confirm your welder lists .045 in wire in the manual.
- Drive rolls and tip: use a V-groove drive roll and a contact tip sized for .045 in solid wire.
- Liner: fit a liner of the right size for the wire diameter.
- Spool mount: check that the spindle holds a 44 lb spool safely, or use a floor stand or adapter.
- Gas: you need a cylinder, regulator and hose.
Pro Tip: Run a short test bead on scrap of the same thickness. Adjust voltage and wire speed until the arc sounds steady and the bead sits flat.
Storage and Handling
Wire rusts if it sits in a damp shop. Keep the spool covered or bagged when not in use, and avoid touching the wire with oily gloves. If the surface looks rusty or the wire feeds roughly, inspect the liner and tip before blaming the wire, and discard wire that has visible rust.
Safety
Wear a properly shaded helmet, gloves and flame-resistant clothing, and weld in a ventilated area. Keep flammable material away from sparks. For structural, pressure or load-bearing work, follow the welding procedure and code that apply to the job.
Is It Worth the Price?
This page does not quote a price because it changes. Large spools usually cost less per pound than small ones, but only if you use the wire. Compare the per-pound cost with a smaller spool and count how many pounds you actually weld before the wire ages.
Pros and Limitations
Pros
- .045 in diameter suits heavier steel and higher amperage
- Large 44 lb spool means fewer spool changes
- Copper-plated, layer-wound wire per the listing
- Material certification is listed as included
Limitations
- 44 lb spool does not fit many machines
- Too hot for thin sheet metal
- Needs shielding gas, so it is not suited to windy outdoor work
- Wire can rust if stored in damp conditions
Related guides: Rumvita ER70S-6 .035 in, 10 lb review | Welding wire spool sizes | MIG wire size chart by metal thickness | 33 lb roll ER70S-6 MIG wire review
Frequently Asked Questions
Is .045 in ER70S-6 wire good for thin sheet metal?
Usually not. The wire and the amperage it needs tend to burn through thin sheet. Use .023 to .030 in wire for thin material.
What shielding gas should I use with ER70S-6?
A 75 percent argon, 25 percent CO2 mix is common, and 100 percent CO2 is also used. Check your welder chart for settings.
Will a 44 lb spool fit my welder?
Only if the feeder and spindle are built for it. Many hobby machines take 2 to 10 lb spools. Check the spool dimensions on the listing and your manual, or use a floor stand.
Can I use ER70S-6 outdoors?
Solid wire needs shielding gas, and wind blows it away. For outdoor work in wind, a self-shielded flux-core wire is usually easier.
How should I store the wire?
Keep it dry and covered. Rust on the wire causes poor feeding and porosity, so do not use wire with visible rust.
The Bottom Line
The ER70S-6 .045-inch MIG welding wire on a 44 lb spool suits shops welding medium to heavy mild steel with a feeder built for large spools. Skip it for thin sheet metal, small machines or gasless outdoor work, and check the spool size and wire diameter against your welder before you order.
Ready to Buy?
Confirm the spool size and your machine rating, then check the current price and details.
