Combination Equipment

BTI has the unique ability to combine multiple technologies into one fully integrated system

A combination machine performs two or more measurement or correction operations on a part in a single automated cycle, on a single fixture, under a single part number and a single data record. Instead of balancing a rotor on one machine, carrying it to a gage on another, and crack testing it on a third, the part is loaded once and leaves finished and fully documented.

Balance Technology has built combination machines since the 1970s, and they are the clearest expression of what we do differently from suppliers who sell one technology out of a catalog. Because we design and build the balancers, the gaging systems, the crack detection systems and the test stands ourselves, we can put them on one base, drive them from one control system, and hold them to one datum scheme. That is much harder to do when the stations come from three different vendors.

Why Manufacturers Combine Operations

The argument for a combination machine is almost always some mix of four things.

Capital cost. Three standalone machines means three bases, three control cabinets, three HMIs, three sets of guarding, three safety circuits and three load stations. Combining operations eliminates most of that duplication. The machine is more complex than any one of the three, but it costs meaningfully less than the sum of them.

Floor space. In most plants we work in, floor space is the binding constraint long before capital is. A combination machine occupies one footprint and needs one operator position, one guarded envelope and one maintenance access path.

Part handling. Every transfer between machines is an opportunity to drop a part, nick a journal, mix up a lot, or lose the orientation you established in the previous operation. Handling is also labor. Combining operations removes transfers, which removes both the scrap risk and the labor.

Traceability. When a crankshaft is balanced on one machine and gaged on another, you have two data records that have to be married together by serial number, and that marriage is often done in a spreadsheet or not at all. A combination machine produces one record per part containing every result, which makes quality investigations far faster and makes the data actually useful for process control.

Technologies We Combine

Any of the following can be stations on a combination machine, and most of our combination builds include three or four of them.

• Balancing — unbalance measurement with automatic correction by drilling, milling, grinding, punching, riveting or weight placement.
• Dimensional gaging — diameters, lengths, runout, concentricity, perpendicularity, taper and form, measured comparatively against a master.
• Mass centering — locating and machining the true mass axis of a forging so subsequent operations start from the axis the part will actually spin about.
• Eddy current crack detection — surface and near-surface flaw detection on machined and ground surfaces.
• Surface finish measurement — roughness parameters on journals, seal surfaces and sealing lands.
• Resonant frequency measurement — acoustic or impact response used to find internal defects, verify material condition, or confirm heat treat.
• NVH testing — noise, vibration and harshness measurement on assembled rotating products.
• Functional and specialized testing — torque-to-turn, backlash, end play, leak, high-speed spin, motor performance and destructive testing.
• Shaft straightening — runout correction by press or peening, closing the loop with the runout the gage station just measured.

Combinations We Build Most Often

Balance plus dimensional gage. The most common request we see. The part is measured for unbalance and for the critical diameters and runouts in the same cycle. Gaging results are frequently used to reject the part before the balance correction is wasted on it.

Gage plus crack detection. Common on machined rings, gears, hubs and rotor components where the dimensional inspection and the flaw inspection would otherwise be two separate cells. Both operations want the part rotating on a precise axis, so they share the spindle naturally.

Balance plus crack detection. Used on flywheels, clutch components, brake rotors and similar discs. The balancer already spins the part on a repeatable axis; adding eddy current heads to that spindle is a small increment of hardware for a whole additional inspection.

Gage, straighten, re-gage. A closed-loop cell for shafts, armature and rotor stacks: measure runout, calculate the correction, straighten, and verify. The verification is the reason the cell exists, and it only works if the measurement and the correction share a datum.

Mass center plus balance. For crankshafts and similar forgings, where locating the mass axis first dramatically reduces the correction the balancer has to make and keeps the counterweights within their machining envelope.

Assembly plus test. Where a press, retaining ring insertion or a fastening operation feeds directly into a balance or functional test stand, so an assembly defect is caught in the same cycle that created it.

One Fixture, One Datum Scheme

This is the part that separates a real combination machine from three machines bolted to a common bedplate.

Every measurement is made relative to something. If your balance station indexes the part on its bearing journals and your gage station indexes it on a pilot diameter, the two stations are describing two different parts, and the numbers they produce cannot be reconciled when something goes wrong. Worse, an operation that corrects the part — drilling, straightening, grinding — is correcting it relative to whatever axis the correction station holds it on, which may not be the axis the customer cares about.

When we design a combination machine, the datum scheme comes first and the station layout comes second. We work from the print, identify which features are the functional datums, and build the fixture so that every station either uses those same datums or has a defined, characterized relationship to them. If the part drawing uses geometric dimensioning and tolerancing, the datum references on that drawing are what the fixture is built to simulate.

The payoff is that results from different stations are directly comparable, and a correction made at one station can be verified at another without an argument about whose axis was right.

How Stations Are Arranged

There are three practical layouts, and the right one is set by cycle time and part size.

Single station, sequential operations. The part is loaded once and stays put while different tooling comes to it. Simplest, smallest, and the best choice when the combined cycle still fits the takt time. Also the easiest layout to hold a single datum scheme, because there is only one fixture.

In-line transfer. Stations in a row with the part indexed from one to the next. Each station works on a different part simultaneously, so throughput is set by the slowest station rather than the sum of all of them. Requires that the transfer preserve or re-establish part orientation.

Rotary dial. Stations arranged around an indexing table. Compact for its throughput and well suited to smaller parts with four to eight operations. Load and unload can share a station or occupy separate ones.

For heavier parts, or where the operations have very different cycle times, we sometimes recommend two machines rather than one. Balancing a part in twenty seconds and then holding it for a ninety-second leak test means the balancer sits idle two thirds of the time. Combination is a design choice, not a doctrine.

One Data Record Per Part

A combination machine writes a single record containing every result for that serial number: unbalance before and after correction, correction amounts and locations, each gaged dimension, crack detection pass or fail and signal amplitude, surface finish parameters, test results, timestamps and operator or shift identification.

That record can be written to a local database, exported to your plant systems, or pushed over the network to a quality data system. Because it is one record rather than three, trend analysis across operations becomes straightforward: you can ask whether the parts that fail crack detection also show a particular dimensional signature, and get an answer in an afternoon rather than a project.

Machines are typically supplied with a PC-based control system. When an older BTI combination machine needs current operating system support, networking, or modern data export, that is usually a PC upgrade rather than a new machine.

When a Combination Machine Is the Wrong Answer

We would rather tell you this before you buy one.

Combination machines are less flexible than standalone machines. If two of the operations serve different part families with different volumes, splitting them lets each run to its own schedule. If one station goes down for maintenance, the whole machine is down, where three standalone machines would leave you running at two thirds capacity. And if your operations have wildly mismatched cycle times, combining them wastes the capacity of the fast stations.

The cases where combination clearly wins are: high volume on a stable part family, operations with comparable cycle times, measurements that benefit from sharing a datum, and a plant where floor space is scarce. Most of the machines we build fit that description, but not all applications do.

What We Need to Design One

A useful conversation about a combination machine starts with:

• Part drawings, including the datum scheme and the tolerances that matter
• The operations you want combined, and the specification each one is held to
• Part weight, maximum diameter and length, and the range across the family
• Required throughput in parts per hour, and the takt time you have to hit
• Correction method, if the part is to be corrected rather than only measured
• How parts arrive and leave — manual load, conveyor, robot, dunnage
• Available floor space, ceiling height, utilities, and any plant standards for controls
• Data requirements: what has to be recorded, where it has to go, and in what format

From that we can tell you honestly whether one machine is the right answer, and what it would look like.

Related Equipment

Combination machines are assembled from the same technologies we build as standalone equipment: balancing machines, dimensional gaging systems, eddy current crack detection systems, surface measurement systems, resonant frequency measurement systems, NVH and specialized testers, shaft straighteners and automated assembly systems.

Frequently Asked Questions

How many operations can one machine perform?
We have built machines with as few as two stations and as many as eight. The practical limit is set by cycle time and by how many distinct fixtures the datum scheme can tolerate, not by a hardware ceiling.

Does combining operations hurt accuracy?
No, and it frequently helps. Each station uses the same measurement hardware it would use standalone. The accuracy gain comes from eliminating the refixturing between operations, since refixturing is often the largest single contributor to measurement variation in a multi-machine process.

Can you combine measurement with correction?
Yes. Most of our combination machines both measure and correct — balancing with automatic drilling or milling, straightening after runout measurement, mass centering before machining. Correction followed by verification in the same cycle is one of the strongest reasons to combine.

Can a combination machine handle more than one part number?
Yes, with tooling changeover and stored part programs. How quickly it changes over depends on how similar the parts are. Parts within a family that share a datum scheme can often change in minutes; parts that need a different fixture take longer.

Can you add a station to a machine we already own?
Often, yes. Adding crack detection to an existing balancer, or gaging to an existing test stand, is a common rebuild and retrofit project. We also retrofit machines built by other manufacturers.

Who supports the machine?
We do, directly. Because every station was designed and built by Balance Technology, support is one phone call rather than a negotiation between vendors about whose subsystem caused the problem. That single point of responsibility is, for a lot of our customers, the real reason they combine.