Industrial Plastic Injection Molding Machine Servo Drives: W

Industrial Plastic Injection Molding Machine Servo Drives: Why Drive Family, Encoder Resolution, and Brake Logic Come Before the Quote

A servo drive on a plastic injection molding machine is not interchangeable across families, even within the same brand and the same series: the suffix structure, encoder protocol and brake-driver output decide whether the replacement will read the motor, hold the brake and report back to the controller. We are an independent China-based industrial automation distributor and sourcing desk, and on a servo inquiry the work is line by line, with the drive family, encoder resolution, brake logic and cable set checked against the machine's own documentation before a quotation is issued. The substitution decision is the buyer's engineering call.

What the servo drive actually does on an injection molding machine

A modern electric or hybrid injection molding machine uses servo drives on at least four axes: the injection axis (the screw position and the plasticising torque), the clamp axis (the platen travel and the mould-closing force), the ejector axis, and in some platforms the carriage or the core-pull axis. Each axis has its own dynamic profile — the injection axis is short-stroke and high-bandwidth, the clamp axis is long-stroke and high-inertia, the ejector is short and very repeatable. That is why a single drive family from one rail does not transplant cleanly onto another rail, even when the manufacturer publishes the part as compatible with a different axis on the same platform.

This matters when a procurement officer looks at a failed drive and asks for the same drive the line already has. The drive on the injection axis may share its part number prefix with the drive on the clamp axis and still be configured for a different current rating, a different encoder protocol, a different brake-driver output, and a different safe-stop input. Two amplifiers that look identical from the outside can carry firmware revisions that change the way the regenerative energy is absorbed, the way the position loop is closed, and the way the controller handshakes the servo-on signal. Looking at the outside is not the same as looking at the inside.

The four-line check we run before quoting

For every servo inquiry on an injection molding machine, we run the same four-line check before the quotation goes out. The four lines are not a marketing framework — they are the four questions a desk has to answer before it can responsibly issue a line on a quote.

Drive family and rail. The drive family is the published series name and the rail it belongs to within that series. Fuji Electric Sigma-X servos in our catalogue (PXH9S211-CVRA0, PXH9S211-CVR00, PXH9S201-CVRA0, PXH9S201-CVR00, PXH9S211-CV0A0, PXH9S211-CV000, PXH9S201-CV0A0, PXH9S201-CV000, PXH9S211-3VRA0, PXH9S211-3VR00, PXH9S201-3VRA0, PXH9S201-3VR00, PXH9S211-BVRA0, PXH9S211-BVR00, PXH9S201-BVRA0, PXH9S201-BVR00, PXH9S211-AVRA0, PXH9S211-AVR00, PXH9S201-AVRA0, PXH9S201-AVR00 and the adjacent variants) are catalogued as same-family units, but the suffixes encode the supply class, the option card population and the safety-stop configuration. A drive labelled CVR is not the same as a drive labelled CV — the suffix structure is published, and a service technician will read it before the drive is pulled for shipment.

Encoder resolution and protocol. The encoder is the closed-loop feedback device, and its resolution and protocol decide whether the replacement drive can read the existing motor. Incremental encoders report a fixed pulse count per revolution (5,000, 8,192, 17-bit serial, 23-bit serial); serial protocols carry initialisation parameters the drive has to load on power-up. A drive configured for a 17-bit serial encoder will not behave the same way when paired with a motor carrying an 8,192-line incremental encoder, even if both encoders mount on the same shaft. We name the encoder that was on the failed drive before we quote, because the cost of finding out the wrong protocol at commissioning is paid for in downtime the buyer did not budget.

Brake logic and the brake-driver output. Plastic injection axes use a holding brake on the injection motor to prevent the plasticised melt from being pushed back through the screw when the machine holds the mould closed. The brake is energised to release and de-energised to hold; the drive has to provide a brake-driver output that matches the brake coil voltage and the brake release timing. Mixing a 24 V DC brake-driver output with a 90 V DC brake coil burns the brake; mixing a DC-output drive with an AC-rated brake leaves the brake stuck on or stuck off. The brake voltage is on the failed drive's nameplate and in the machine builder's manual, and we read it before the line goes on the quote.

Cable set, connector and option cards. The cable between the drive and the motor is not a generic item — it carries the encoder wires, the motor-power wires and, on some platforms, the brake wires inside one outer jacket. The connector on the drive side has to match the connector that was on the failed unit; the option-card population (feedback, safety, communication) has to match what the controller expects to see on the bus. We report the cable and option-card state per line, because a drive that arrives without the right option cards is not a usable line, and a buyer who learns that at commissioning has paid for a part out of order.

Three conditions, kept distinct per line

We state the condition of every servo line on the quote, and we do not blend the categories. New-surplus drives come from documented channel sourcing — sealed packaging, original manufacturer markings, intact option cards and the warranty the channel provides. Refurbished drives are bench-tested, and the bench record names the axis the drive was tested on, the load profile it was driven under and the parameters that were read back; the bench record is what the per-line warranty refers to. Used drives are inspected and shipped as pulled, and the inspection notes state what was checked and what was not — we do not describe an untested drive as tested, and we do not describe a used drive as refurbished.

If the line is the only one we have for that drive family, we say so rather than substituting a sister drive from a higher current rating. Substituting a sister drive from a higher current rating is a documented cross-reference decision that has to go through the twelve-axis comparison, and the comparison has to be visible to the buyer's engineering team before the drive ships.

The twelve-axis comparison we publish when a cross-reference is on the table

When a buyer asks for a substitute — because the original drive is on allocation, or because the original drive has been discontinued, or because a sister drive is closer to the dock — we run the comparison on the twelve axes the desk uses as a baseline. The twelve axes are: form, fit, and outline; dimensions; terminal and interface assignment; electrical ratings; function and I/O specification; firmware and hardware version; communication protocol; mechanical parameters; environmental class; ingress protection and temperature; materials; and certification and lifecycle status. Each axis is reported as matched, differs, or unknown, and the unknown axes are named rather than filled in with the favourable cell.

We do not write any of the assertions that imply interchangeability without verification on a desk line. The desk's claim ladder only goes up to "mounting and terminal interface matches on paper — verify against the original manufacturer datasheet and your own qualification process" without a customer qualification record, and the verification instruction is repeated on the quote. The substitution decision is the buyer's engineering call, and our job is to put the comparison in front of that call with the unverified axes visible.

Fail-safe cases the desk declines or flags at inquiry

A substitution proposal that touches a fail-safe case is either declined at inquiry or returned to the buyer's engineering team with a fail-safe flag. The fail-safe cases the desk names are not a blacklist — they are the cases where the substitution question has to be answered by the machine builder or by a qualified engineer rather than by the desk.

A servo drive inside a category-1 stop or safe-torque-off loop. A stop circuit that protects the operator is bound to the manufacturer's declaration of conformity. Substituting the drive changes that declaration, and the substitution is declined. The original part number stays on the quote.

A servo drive inside a mould-protection interlock. A mould-protection interlock closes the safety gate during the mould-close stroke. The interlock relies on the drive's safe-stop input and on the way the controller handshakes the servo-on signal. Substituting the drive changes the interlock's tested behaviour, and the substitution is declined.

A servo drive on a production line still under manufacturer warranty. When the machine is still inside the original builder's warranty and tied to a service contract, a third-party drive voids the warranty. We keep the original part number on the quote.

A servo drive where the unverified axis is the axis that matters. If the substitution will fail if the encoder protocol does not match, and the encoder protocol is the axis the desk cannot verify, the substitution is declined and the original part number is kept on the quote.

A servo drive on a clean-room or aseptic line. A clean-room line carries its own qualification trail, and introducing a third-party used amplifier onto that line is a qualification event the buyer must decide, not a sourcing event the desk decides. The substitution is declined.

Sourcing a Fuji Electric Sigma-X drive from the catalogue

The Fuji Electric Sigma-X servo platform appears in the desk's catalogue across the PXH9S211 and PXH9S201 sub-families, with current-rating variants and option-card configurations covered in the SKU record. The published suffixes (CVRA0, CVR00, CV0A0, CV000, 3VRA0, 3VR00, BVRA0, BVR00, BV0A0, BV000, AVRA0, AVR00, AV0A0, AV000) are the visible handle for the suffix structure the desk checks before shipment. A line that comes in as PXH9S211-CVRA0 is not the same desk line as PXH9S211-CV000, and we treat them as separate lines even when the manufacturer labels them as related. Per-line condition (new surplus, refurbished, used) is stated on the quote; per-line MOQ is quoted per line because it is the upstream supplier's MOQ that decides it; per-line lead time is quoted per order because it depends on what is in the channel at the time of the order.

For a buyer running an injection molding line, the per-line workflow is: send the failed drive's part number (or a photograph of the drive nameplate together with the machine builder and the machine serial number); the desk identifies the drive family, the encoder protocol and the brake voltage from the part number and the catalogue; a quote is prepared with the drive family, the condition, the MOQ, the price, the lead time and the brake/encoder notes per line; the buyer confirms; the desk pulls the drive, bench-tests it if it is refurbished, photographs it before dispatch and ships under the commercial term stated on the quotation.

What an independent desk does not do on a servo inquiry

We do not hold a manufacturer certification on Fuji Electric Sigma-X or on any other brand we catalogue, and we do not claim compatibility that the manufacturer has not documented. We do not certify a substitution on the manufacturer's behalf; we publish the comparison with the unknown axes named, and the substitution decision rests with the buyer's engineering team. We do not claim a fixed transit time; lead time is quoted per order because it depends on the channel and the destination. We do not issue EAC or TR CU documentation on the buyer's behalf, and we do not arrange conformity assessment for the buyer. We do not repair a drive on the buyer's behalf, and we do not represent a repair done elsewhere as a desk service.

What the desk does do is run the twelve-axis comparison with the unverified axes visible, state the condition per line, ship with a per-line photograph before dispatch, and decline the work at inquiry when the work falls inside one of the fail-safe cases above. We screen end users and end uses, classify before quoting, and decline transactions that cannot be screened.

The line on a Russian or CIS buyer's desk

For a Russian or CIS buyer running an injection molding line, the desk's process is the same line-by-line process that runs for any other buyer, with the additional step of confirming the destination's commercial term on the quotation. Delivery is arranged under EXW, FCA, DAP or DDP as the quotation states — the desk does not present DDP as a default because the right term depends on the destination, the value and the buyer's own customs arrangements. The desk does not publish a fixed transit time to Moscow or to any other regional destination, because the published time would be a service promise rather than a quoted term. The commercial invoice and packing list travel with the consignment, and the certificate of origin or test documentation is confirmed per line where the source can provide it.

What the desk does not do on a Russian or CIS inquiry is the same as what it does not do elsewhere: no EAC or TR CU on the buyer's behalf, no customs clearance outside the DDP scope of the quotation, no circumvention of duties, sanctions or export controls, and no destination promise that the quotation has not stated.

The takeaway

Send us the failed drive's part number (or a photograph of the nameplate) together with the machine builder and the machine serial number, and our sourcing desk will prepare a per-line RFQ with the condition, MOQ, lead time and the encoder and brake notes stated for each line. The substitution decision, where one is on the table, is the buyer's engineering call; the desk's job is to put the comparison in front of that call with the unverified axes visible, and the comparison is verified against the original manufacturer datasheet and the buyer's own qualification process. For lines that fall inside one of the fail-safe cases above, the desk declines at inquiry rather than taking the work and failing it later.

by aoctrl sourcing desk · Last updated 2026-09-28 · Data through: September 2026

Data Notes: This article uses published Fuji Electric Sigma-X servo drive family part numbers (PXH9S211 and PXH9S201 sub-families, with suffix structure CVRA0 / CVR00 / CV0A0 / CV000 / 3VRA0 / 3VR00 / BVRA0 / BVR00 / BV0A0 / BV000 / AVRA0 / AVR00 / AV0A0 / AV000) drawn from the desk's catalogue records. The four-line check, the per-line condition discipline, the twelve-axis methodology, the fail-safe list and the boundary on EAC, transit time, conformity and substitution certification language follow the desk's published service scope and the red lines in the operator references. No external URLs are cited in the body; the evidence trail is internal.

We are an independent industrial automation distributor and sourcing desk based in China. We are not an authorized distributor of Fuji Electric, nor of any other brand we catalogue. We do not hold EAC or TR CU certification, ISO 13485, SIL/PL, ATEX, UL or any equivalent conformity credential. We screen end users and end uses, classify before quoting, and decline transactions that cannot be screened.

FAQ

Why does the same drive family have different part numbers?

The suffixes on a Fuji Electric Sigma-X servo drive encode the supply voltage class, the option-card population and the safety-stop configuration. Two drives that share the same family prefix (PXH9S211) and differ on the suffix (CVRA0 vs CV000) are not interchangeable across axes; the axis they were designed for decides which suffix is correct. We treat each suffix as a separate line on the quote.

Can a Sigma-X drive be substituted for a drive from another brand?

Only after a twelve-axis comparison on form, fit, electrical, function, firmware, communication protocol, environmental class and certification lifecycle has been run, with each axis reported as matched, differs or unknown. The substitution decision rests with the buyer's engineering team. We do not write any assertion of interchangeability on a desk line, the comparison is verified against the original manufacturer datasheet and the buyer's own qualification process, and we name the unknown axes rather than fill them in.

What condition is the drive you send?

Condition is stated per line. New-surplus drives come from documented channel sourcing with sealed packaging. Refurbished drives are bench-tested and the bench record names the axis and the load profile. Used drives are inspected and shipped as pulled, and the inspection notes state what was checked. We do not describe an untested drive as tested, and we do not describe a used drive as refurbished.

Will a Sigma-X drive from a sister series work on the injection axis?

It depends on the axis current rating, the encoder protocol and the brake-driver output. The injection axis is short-stroke and high-bandwidth; substituting a drive from a sister series that was designed for a different axis can change the position loop, the regenerative absorption and the safe-stop input. We run the comparison with the unverified axes named, and the result is verified against the original manufacturer datasheet and the buyer's own qualification process before the line goes on the quote.

What if the encoder protocol on the replacement does not match the motor?

The drive will not close the position loop and the machine will not index. We name the encoder protocol on the failed drive before we quote, and we report the encoder protocol the desk found on the replacement. If the desk cannot verify the protocol on a used or refurbished line, we say so on the quote rather than guessing.

Do you issue an EAC certificate for a Sigma-X drive shipped to Russia?

No. The desk does not hold EAC or TR CU certification and does not apply for it on the buyer's behalf. Conformity assessment for import is arranged by the importer. What the desk provides is the commercial documentation described on the quotation; the importer handles the conformity side.

How is a Sigma-X drive packed for an international shipment?

Electronic modules are packed to protect against static and mechanical damage, and the packing list reflects the lines in the consignment. Photographs before dispatch are standard for used and refurbished items, and video is provided where the item can be powered. The packing method is stated on the quotation, and a destination or handling constraint that needs a particular packing is confirmed at order time.