Some of those machines have been running production for two decades. When your engineer designed a $400 million medical device around a percussion weld spec, nobody questioned the process — because it worked. It still works.

But capacitors age. Contacts wear. And when the machine that's been faithfully bonding tungsten to nickel every 4 seconds finally starts throwing inconsistent arcs, you need to know: what's the upgrade path, and will my weld schedules carry over?

Short answer: yes. The Model 858 Percussion Welder is the direct successor to both the Superior 528-series and the MTI 628. Same process physics. Same weld joint metallurgy. Dramatically better controls.

The engineering punchline: All three generations use short, high-energy capacitor discharges and rapid mechanical motion to forge direct, filler-free joints. The 858 didn't reinvent percussion welding — it just gave operators front-panel access to every parameter that used to require a screwdriver and a prayer.

Three machines. One process. Each generation refined what mattered without changing what worked.

The Foundation

Superior Model 528 Series

The 528G and 528A power supplies were among the first commercially available percussive-arc welders. They proved the concept in production: short, high-intensity discharges could reliably weld pins, tabs, and thermocouples — including dissimilar metal combinations that made conventional processes sweat. Referenced in multiple patents (including US4417120) as the benchmark power source for percussive arc joining.

The Refinement

MTI MicroWelding Model 628

Building on the 528 foundation, the 628 broadened the usable energy range, added selectable polarity from the front panel, and lowered the required weld force — critical for delicate parts with low columnar strength. Same percussive-arc physics, but now an operator could tune for nitinol, aluminum, tungsten, and copper without the process equivalent of open-heart surgery on the power supply.

The Current Standard

Model 858 Percussion Welder

The 858 is a full micro-welding control platform. Fine adjustments to actuator velocity, timing delay, weld voltage, pulse width, polarity, and capacitance — all from the front panel. Pair it with the 726 Bench Fixture for precision alignment and the optional Percussion Weld Monitor for pass/fail waveform analysis. Sub-3 ms welds with near-zero joint resistance, documented and repeatable across medical, aerospace, automotive, electronics, and defense applications.

The process column reads the same across all three rows. That's the point — percussion welding works. The controls are where three decades of engineering investment shows up.

Notice the last row. Three generations of engineering and the weld time didn't change. When you're already faster than a blink (literally — it takes 400 ms to blink and about 2 ms to percussion weld), the wins are in control, repeatability, and documentation. The 858 delivers all three.

<2ms Typical weld cycle 30+ Material combinations documented 0 Consumables required ≈0Ω Added joint resistance

Bring your current weld schedules. We'll show you exactly how they translate to the 858 — live, on your materials if you bring them. No PowerPoint. Real welds.

This is the part that matters when you're justifying the upgrade to procurement. (We've been there. We speak spreadsheet.)

Your Weld Schedules Transfer

If you've got a binder full of hand-tuned 528 or 628 parameters — actuator settings, capacitance, voltage, polarity — those are your starting points on the 858. The physics is identical. You'll likely refine them further because the 858 gives you finer control than your old machine could, but you're not starting from zero. That binder is still gold.

Your Process Knowledge Transfers

Everything your operators know about material prep, fixture alignment, polarity effects on copper-to-stainless joints, and what "too explosive" sounds like — that knowledge is directly applicable. The 858 has a faster learning curve than the machines it replaces, but the process intuition your team has built? That's an asset, not a liability.

Your Qualification Data Is Defensible

For aerospace and medical applications where re-qualification is the four-letter word: the 858 produces the same metallurgical bond via the same arc-percussive process. Same joint type, same filler-free autogenous weld, same minimal HAZ. The control documentation gets better, not different — which is usually what auditors want to hear.

Real talk from the shop floor: We've seen engineers treating their 528 like a 1992 Toyota pickup — "it still runs, don't touch it." We get it. But when your capacitors are original equipment from the Clinton administration and your documentation is a sticky note on the power supply, the 858 isn't just an upgrade. It's risk mitigation that happens to also make better welds.

Where the 528 and 628 were standalone power supplies, the 858 is the control center of an integrated system. Here's what you're actually getting:

858 Percussion Welder

The brain. Programmable energy and process controls with front-panel access to actuator velocity, timing delay, weld voltage, pulse width, polarity, and capacitance. Store and recall weld schedules instead of re-dialing parameters for every job changeover.

Model 726 Bench Fixture

The hands. X, Y, and Z-axis alignment with precision gap control and rapid mechanical motion to forge the weld. This is the dedicated fixture that turns "I think the alignment was close enough" into "the alignment is documented and repeatable."

Percussion Weld Monitor (Optional)

The quality inspector that never takes a coffee break. Waveform analysis on every weld, pass/fail classification, and data capture for your QC requirements. Particularly valuable for medical and aerospace where you need to prove every joint, not just sample them.

Superior is no longer manufacturing the 528-series machines, and original parts are increasingly difficult to source. The 858 is the direct technological successor — same process, modern controls. If your 528 is still running but aging, we can evaluate your current setup and show you exactly how the transition works with your existing weld schedules and fixtures.

The 858 uses the same arc-percussive process and produces the same metallurgical bond type as your current machine. Many customers find that re-qualification is streamlined rather than started from scratch, because the process fundamentals are identical and the 858 actually provides better documentation and monitoring capabilities. That said, re-qualification requirements are application-specific — we recommend discussing your particular standards with your quality team and ours.

Operators who are already proficient with the 628 typically get comfortable with the 858 in hours, not days. The process is the same — what changes is the precision of the controls. Most of the transition time is spent discovering that parameters you couldn't previously adjust are now available, which usually leads to better weld quality, not disruption.

The core capability was always there — percussion welding inherently handles dissimilar metals. What the 858 adds is wider, more precise energy control that makes previously "marginal" material combinations reliably producible. Our weld schedule database covers combinations including copper, tungsten, tantalum, molybdenum, nickel, aluminum, stainless steel, niobium, platinum, and many others across wire diameters from .005" to .070". Check our full schedule database →

Absolutely. We run live demonstrations on your materials, with your geometries, at our facility in Denver. Bring your parts, bring your current weld spec, and we'll show you what the 858 does with them. No obligation, no PowerPoint — just metal on metal. Schedule your demo →

It welded thermocouples when "the internet" was still a novelty. It bonded dissimilar metals before your quality system went digital. Give it a proper send-off — and give your operators the controls they've been working around for years.

The Percussion Welder Model 858 is a top micro arc welding machine. It allows two wires of similar or dissimilar metals to be welded together quickly, efficiently, and with precision and control.

The Model 858 is the control system for the bench unit, and it offers precision adjustment for different metals, diameters of materials, and the specific current required for the process. This control over the micro welders equipment is user-friendly, with dial control over the actuator, delay, and weld energy voltage control.

The user can also adjust the mode, pulse, polarity, and capacitance for each weld using clearly marked switches on the panel. The system is ready to use upon arrival, and with intuitive operation, our micro spot welding machine is easy to integrate into any process.

Our mirco welding equipment is ideal for manual operation, but it is easily adaptive and integrated into automated production lines and processes. The Model 858 micro welding machine system comes with the Model 726 Bench Fixture and the optional Percussion Weld Monitor that tests welds for customizable good/no good quality control.

If you have any questions about our micro welding machines, or if you are struggling to find a micro welding solution, call us at 303-536-7838 or reach out to us online.

Advanced Control Features

The 858 Percussion Welder offers a suite of advanced control features that make it an indispensable tool for precision micro-welding. The front panel is equipped with user-friendly controls that allow operators to fine-tune every aspect of the welding process. From adjusting the actuator and delay settings to controlling the weld energy voltage, the 858 provides unparalleled precision and flexibility.

Operators can select from various mode settings, including regular and heavy-duty, to match the requirements of their specific application. The ability to control pulse width, polarity, and capacitance ensures that each weld is optimized for strength and durability. These features make the 858 Percussion Welder a versatile solution for a wide range of micro-welding tasks.

If you’re like us, sometimes a picture (or video) is worth a thousand words. Watch our video showing you step-by-step how easy Percussion Welder 726 Bench fixture is to operate.