If you run a friction bolt production line, you know machine specs only tell part of the story. The real cost shows up during changeovers—when tooling comes off, a new set goes on, and the line takes time to return to full production. For split-set friction bolts, that downtime matters even more. 

In this guide, we'll walk you through the tooling setup, step-by-step changeover process, common mistakes that waste production time, and what to consider when choosing or upgrading a friction bolt machine.

What Makes Split Set Tooling Different From Standard Roll Forming Tooling 

A split-set friction bolt is not a simple shape. What you do is take a piece of sheet metal and roll it into a tube that has a taper along the entire length of the bolt. The taper is the reason for the friction hold when the bolt is inserted into the undersized hole.

A typical tooling stack for this job includes:

• Forming rolls: A progressive series of roll passes that gradually curl the flat strip into a tube shape, stage by stage rather than all at once.

• Slot-forming and edge-control tooling: Controls the open slot that runs the length of the bolt and keeps the edges from overlapping or gapping incorrectly.

• Taper-forming station: Either a mandrel-assisted roll or a dedicated tapering pass that produces the gradual diameter reduction along the bolt's length.

• Sizing and calibration rolls: The final passes that lock in the finished outer diameter and roundness before the bolt leaves the forming section.

• Cut-off tooling: A shear or die set matched to the target bolt length, positioned after the forming and calibration stages.

None of this tooling can be switched out between diameter sizes without readjustment. It is not like if you use your roll pass for 39mm and switch out the rolls and now have a good 46mm roll. You have to move all of the rolls together. Friction bolts are made out of spring steel and not mild steel; thus, the tooling wear is different than something like a roofing panel.

If you want to see how BMS approaches tube-shaped forming tooling more broadly, our tube roll forming machine range and the octagonal steel tube roll forming machine are good reference points for how progressive tube tooling is built and staged.

Step-by-Step Changeover Process 

Pre-Changeover Preparation

Before any work is done on the bolt, lockout/tagout the machine. Don’t take this as a tick-the-box activity because roll forming machines have stored energy through tensioned shafts and hydraulics, and changing over the machine is precisely the moment that somebody has to reach into a place that usually stays untouched. After securing the machine, grab the job specification sheet and ensure that you have the right target diameter, length, slot width, and taper angle according to what is written down, not your memory of past jobs.

Next, prepare the proper tooling set beside the machine and make sure that it matches the spec sheet before beginning with any dismantling activities. It would be more accurate to physically verify the roll numbers or codes on the tooling against the spec sheet rather than doing it by eye and size since two sets of rolls with adjacent diameters may appear almost identical at first sight. Half of all changeover problems result from using the wrong set of rolls in the first go and having to reverse steps after a test run fails.

Removing the Current Tooling Set

Loosen the tension in the roll stack in the right sequence, instead of just wrenching bolts loose in a random order. That is the way shafts get scored and bearings get misaligned, and when that happens, the shaft repair job becomes more complicated than the changeover itself. Every time a roll is pulled out, take a quick look at it to see if there is wear, chipping, or buildup—that little check will save you money later.

Now that the rolls are all out of the machine, store them properly: clean, protected against corrosion, and marked in such a way that the next operator who pulls them out does not need to make any guesses about them. A tooling cart or rack that is classified by roll diameter saves a lot of time in this process.

Installing and Aligning New Tooling

Install the roll setup with proper orientation; it is easy to install a roll backwards or out of order while working rapidly, and the problem becomes obvious only during a failed trial run. Make the shaft spacing and shimming for the new diameter and gauge combination based on the documentation, not by comparison with the previous job.

This is also the time when you have to align guide rails and taper-forming parts. Alignment of the guide rails determines the stability of strip entry into each pass, and even the slightest misalignment leads to growing errors during forming. Misalignment of the guide rails is the primary reason for waste during the first run after changeover, and it often takes less time to do it properly initially than to fix problems caused by it in three failed trials.

Calibration and Trial Run

Take your test strip all the way through the whole length before moving to the production coil. Measure the diameter of the tube, slot size, taper, and length in terms of the tolerance in different spots along the test strip, and not only the first couple of feet of it. The thing is, any deviation in taper tends to be inconsistent rather than constant, and so it may happen that it would be overlooked based on the measurements taken at the beginning of the piece.

If anything's out of spec, this is where you adjust; not after you've run a full coil. Try to adjust one parameter at a time and then make another trial piece, because it is hard to determine what specific setting caused the required change if you adjust several settings at once.

Cut-Off and Length Adjustment

Set the shear or cut-off die for the new bolt length and confirm the cut is square with no problematic burr. A clean cut-off matters more on friction bolts than it might seem: a burred or angled end can affect how the bolt seats and grips once it's driven into the borehole, and a customer complaint about seating problems often traces back to cut-off quality rather than the forming process itself. 

Final Sign-Off and Production Start

Run through a short quality checklist (diameter, taper, slot, length, cut quality) before releasing the line to full-speed production. It's worth pulling a handful of pieces from across the trial run rather than just the last one, since a tooling set that's drifting slightly will often show it more clearly over several pieces than in a single sample.

Log the final settings against the job spec: shim combinations, shaft spacing, and any adjustments made during trial. That log is what turns next month's changeover from a repeat of today's trial-and-error into a quick lookup, and it's one of the most underused tools on most production floors.

Common Changeover Mistakes That Cost Time or Quality 

• Skipping the trial run to save a few minutes: This is the quickest route to scrapping a coil that could have been produced in just fifteen minutes.

• Reusing worn shims instead of following the spec sheet: When your shim is only a little bit out of tolerance, it will quietly affect the diameter and taper of your entire run.

• Poor tooling storage between jobs: Improper storage of the tooling after each job: Corroded, nicked, or out-of-alignment rolls will add time and unpredictability to your next changeover.

• Not documenting settings: Without this record, each changeover becomes a new guessing game, even if you have run this particular size many times before.

• Underestimating taper calibration: A taper that is barely off your specifications on the gauge may not perform to standards underground.

• Mismatched tooling hardness for the strip being run: Spring steel wears tooling faster than mild steel, and tooling that isn't rated for it will show premature wear sooner than expected.

How Tooling Design Affects Changeover Speed 

Some of this comes down to procedure, but a lot of it comes down to how the tooling itself was engineered. When you're evaluating a machine or planning a tooling upgrade, look for:

• Modular roll cassettes: Cassettes containing rolls instead of individual shafts reduce changeover time because there is only one item being changed out instead of many.

• Quick-release shaft systems: Quicker tension changes with no loss of alignment.

• Standardized shimming across a size range: If the shims can be the same across all diameter classes, then operators will have more time to set up the correct amount.

• Pre-marked or pre-set adjustment points: Physical reference marks that let operators return to known-good settings quickly instead of measuring from scratch every time.

• Wear-resistant tool steel and surface treatment: Better roll material means longer runs between reconditioning, which means fewer changeovers overall.

Cut-off and auxiliary equipment matter here too. A well-matched electric cutting machine or a properly sized hydraulic decoiler upstream of the forming section keeps the rest of the line from becoming the bottleneck once the tooling itself is dialed in.

Maintenance Practices That Keep Changeovers Fast Over Time

Tooling that's well maintained stays fast to change over; tooling that isn't gets slower every month. A few habits make the biggest difference:

• Routine inspection: Inspect wear surfaces, roll surface condition, and bearing looseness according to an established schedule, and not only in instances where equipment is starting to produce defectives.

• Cleaning and storage protocols: Store and clean the tooling between operations so that it will go back into service aligned rather than fighting itself.

• Reconditioning vs. replacement decisions: Understand your maximum wear prior to the operation so that the decision isn’t made under pressure.

• A tooling inventory log tied to job specs: This converts the “what roll set do we need for this job” question from ten minutes in the tool crib to five seconds.

If your strip prep equipment (slitting or cut-to-length) is part of the same changeover, it's worth applying the same discipline there. BMS's metal slitting machines and cut-to-length line machines pages cover how upstream prep equipment factors into overall line efficiency.

Choosing or Upgrading a Machine With Changeover Efficiency in Mind

If you're in the market for a new line or thinking about upgrading tooling on an existing one, changeover time deserves as much attention as forming speed. A few questions worth asking any machine builder:

• What's the typical changeover time between the size classes we actually run? Ask for a real number based on your specific diameter range.

• Is the tooling modular, and how many size families does one machine support? That will tell you how much tooling you will have to carry and whether it is major or minor changes that you make when changing diameters.

• What documentation and training come with the machine? The best-designed changeover process won't do anything if your operators don’t know it.

• What's the tooling replacement and lead-time policy? Worn tooling you can't get replaced quickly turns into downtime you didn't plan for.

A machine that scores well on this checklist tends to pay for itself in reduced downtime long before it pays for itself in raw forming speed.

Conclusion 

Changeover efficiency isn't a minor operational detail tucked away in the maintenance manual; it's a direct driver of throughput and cost per bolt. The machines that perform best over the long run are the ones where tooling design and changeover discipline work together, not the ones that just look fastest on paper.

If you'd like to talk through tooling options or changeover optimization for your own line, BMS's engineering team is happy to walk through your specific size range and production volume. You can reach out through our contact page or explore our full range of roll forming machines to see what fits.

FAQs

How long should a tooling changeover take on a split-set friction bolt machine?

The duration of a tooling changeover varies significantly depending on the difference between the two diameter classes. A small change in diameter usually takes less than an hour. A change of the whole diameter is quite a lengthy process.

Can one machine run multiple split-set bolt diameters?

Yes, the vast majority of split-set friction bolt lines are made for covering a certain diameter range via the use of different tooling stacks and not a single fixed roll set.

Does strip material affect the changeover procedure? 

Strip material influences the wear of the tooling more than the actual changeover process. High-strength spring steel used for friction bolts causes more wear of the tooling compared to mild steel. Thus, the condition of the tooling should be checked before every changeover.