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The LK12 ball screw support unit from SYK (Sonyung Industry Co., Ltd.) is a low-profile fixed-side unit built around a 7001A P5 precision bearing set, DF back-to-back assembly, and factory preload that delivers zero axial clearance. It is compatible with C3 through C10 ball screws. Its job is simple: replace tall standard fixed-side units on machines where vertical space is tight but positioning rigidity cannot be compromised. This guide walks through the bearing, preload, starting torque, surface finish, and lead time—so you can confirm LK12 fits your application before you place the order.

Choosing LK12 is not about the 12 mm bore. It is about whether "low-profile body × DF-preloaded bearing × zero axial clearance" matches your machine's space, rigidity, and cleanliness requirements.

SYK has focused on ball screw support units, lock nuts, and motor brackets since 1989, producing them under a single-facility, vertically integrated model with a standard lead time of 1–3 working days and no minimum order quantity.

Why switch from a standard fixed side to a "low-profile" fixed side when space is tight?

A low-profile fixed-side unit solves a height problem: when the machine's structural envelope shrinks but the ball screw's stroke and axial load cannot be sacrificed, you need a shorter housing to fit the available space. The LK12 body stands 38 mm tall (H) and 70 mm wide (B)—a genuinely low-profile design suited to semiconductor equipment, medical inspection, and desktop automation, where every millimeter of build height is expensive.

As automation platforms get more compact, the gap between the Z-axis and the base plate that is left for end supports often comes down to a few millimeters. Standard fixed-side units, such as the taller BK series, tend to interfere in flattened mechanisms. A low-profile design lays the housing flatter and lowers the screw centerline relative to the mounting face, letting design engineers fit the whole drive into a thinner mechanical layer without changing the screw itself.

In other words, going low-profile is not about saving material. It is about preserving the original stroke and rigidity inside a fixed mechanical envelope—an increasingly critical constraint as equipment continues to miniaturize.

What hidden costs come from choosing the wrong fixed side?

The three most common hidden costs of a wrong fixed side are positioning drift, corrosion in cleanrooms, and rework delays—and none of them shows up in the unit price. The fixed side carries the screw's primary axial load, so if preload is insufficient or axial clearance is not controlled, positioning accuracy slowly drifts during reciprocating motion, surfacing as unstable part dimensions and falling yield.

The first trap is axial clearance. If an angular-contact bearing is not preloaded to remove axial play, the screw develops backlash when reversing direction—fatal for applications that depend on bidirectional positioning repeatability. LK12 bearings ship preloaded to zero axial clearance specifically to lock this variable down before it reaches your machine.

The second trap is the wrong surface finish. Using a standard black-oxide unit in a cleanroom or humid environment invites rust and particle shedding that contaminate the space; conversely, paying for a plated unit in a general environment is money spent for nothing. The third trap is discovering a spec mismatch too late, forcing a last-minute material change and re-order that adds days to the schedule. Confirming these three points during selection prevents far more downtime and rework than chasing a lower unit price after the fact.

How do you read the LK12 spec? Bearing, preload, and starting torque explained

Reading the LK12 spec starts with three core numbers: bearing model 7001A, accuracy class P5, and maximum starting torque of 210 gf-cm. Together they set its rigidity baseline and running resistance, and they are your first check on whether LK12 suits your screw grade. LK12 uses DF back-to-back angular-contact assembly with a 30° angular contact angle, preloaded to zero axial clearance—the configuration best matched to ball screw duty.

The bearing is the heart of the fixed side. LK12's standard configuration is a 7001A P5 precision bearing; if you order the version matched to C5–C10 accuracy, the bearing changes to P0 class, which is reflected in the order-code suffix. DF back-to-back assembly spreads the load lines of the two angular-contact bearings outward so the pair carries axial load in both directions at once—exactly the load pattern a ball screw end support needs.

Other key figures include a 12 mm bore (d1), 2-M4 mounting bolts, a housing weight of roughly 0.43 kg, and compatibility with C3–C10 ball screws. SYK machines the housing body, presser plate, spacer, oil seal, and lock nut and preloads the assembly under one roof—so every LK12 that ships is measured, preloaded, and sealed to a single consistent standard.

How do you read the LK12 order code? The suffix logic in one pass

The LK12 order code uses suffixes to separate two dimensions—surface finish and compatible screw accuracy—so once you can read the suffix, you will not order the wrong part. The base LK12 is black oxide, suits C3–C10, and carries a P5 bearing; adding _N means electroless nickel, while _C5 or _C3 maps to different screw accuracy and bearing class.

The full mapping is: LK12 (black oxide / C3–C10 / P5), LK12_C5 (black oxide / C5–C10 / P0), LK12_C3 (black oxide / C3 / P5), LK12_N (electroless nickel / C3–C10 / P5), LK12_C5N (electroless nickel / C5–C10 / P0), and LK12_C3N (electroless nickel / C3 / P5). A simple rule: an N in the suffix means electroless nickel (clean/anti-corrosion); the C5 or C3 digits tie the part to screw accuracy and bearing class.

When ordering, just state the environment (general or cleanroom) plus the screw accuracy, and the correct code follows. If you are unsure, give SYK the application details and let the factory map the model, so a mis-entered suffix never leaves you with a bearing class that does not match the need.

Why do lead time and consistency depend on who makes the part?

Lead time and consistency are tied to the manufacturing model because a vertically integrated factory keeps housing machining, preload assembly, surface treatment, and seal fitting on one line—with no waiting on outsourced parts. SYK has produced under a single-facility, vertically integrated model since 1989, with a standard lead time of 1–3 working days, custom lead time of 5–7 working days, and no minimum order quantity.

For buyers and engineers this matters in three concrete ways. First, lead time is controllable: in-stock items ship immediately and most other standard items are ready within three days, so an urgent top-up will not stall the line. Second, consistency: running every step in-house means the preload amount, axial clearance, and sealing standard for each LK12 batch pass through one process, keeping batch-to-batch variation low. Third, verifiability: SYK backs its support units with quality validation including thrust testing, salt-spray testing, life testing, and axial reciprocating testing, and provides downloadable specs and 2D/3D CAD so engineers can align and calculate at the design stage.

In one line: because measurement, preload, and sealing all run on the same line, LK12 can hold both short lead times and batch consistency.

How do you choose among LK08, LK10, LK12, and LK15—and how do you decide the finish?

Selecting within the LK series is a three-step process: match the bore first, check starting torque and body size second, and decide the surface finish last. The LK series spans four bores—LK08, LK10, LK12, LK15 (8–15 mm)—all compatible with C3–C10 ball screws; larger bores mean higher load capacity, a larger body, and higher maximum starting torque.

The selection logic is direct: match the support-unit bore to the screw's fixed-side journal, then confirm your mechanical envelope can accommodate the corresponding B × H. LK10 and LK12 share nearly the same footprint (both 70 × 38 mm); they differ in bore, mounting bolt (M3 vs. M4), and bearing model—so if the journal is 12 mm, choose LK12 rather than forcing an LK10.

Surface finish comes down to environment: choose black oxide for general factory environments (lower cost), and electroless nickel for cleanrooms, high humidity, or anti-corrosion needs. The rule of thumb—environment decides the coating, screw accuracy decides the suffix digit—keeps the two dimensions separate and the choice correct.

Frequently Asked Questions (FAQ)

Q1: What is the lead time for LK12, and is there a minimum order quantity?

LK12 is a standard item; in-stock units ship immediately and most others are ready within three working days. SYK's standard lead time is 1–3 working days and custom is 5–7 working days, with no minimum order quantity—small-batch and single-unit orders are accepted.

Q2: What bearing does LK12 use, and what is the accuracy class?

LK12 is standard-fitted with a 7001A P5 precision bearing in DF back-to-back angular-contact assembly with a 60° contact angle, preloaded at the factory to zero axial clearance, with a maximum starting torque of 210 gf-cm. Versions matched to C5–C10 accuracy use a P0-class bearing.

Q3: How do I choose between black oxide and electroless nickel?

Choose black oxide for general factory environments—lower cost and broadest use. Choose electroless nickel (suffix N) for cleanrooms, high humidity, or anti-corrosion needs. The choice is driven by operating environment, not by price.

Q4: Which ball screw accuracy grades is LK12 compatible with?

LK12 is compatible with C3–C10 ball screws. The order code ties screw accuracy to bearing class: C3–C10 corresponds to a P5 bearing, C5–C10 to a P0 bearing (suffix _C5), and C3 only to _C3.

Q5: Are 2D/3D CAD files available, and can you machine the screw shaft end?

Yes. SYK provides downloadable catalogs and 2D/3D CAD files for LK12 so engineers can align parts at the design stage, and screw shaft-end machining can be supported on request—confirm the exact machinable range with the factory directly.

Q6: LK12 is a fixed side—which support side should I pair it with?

LK12 is a low-profile fixed side and pairs with a low-profile support side (the LF/LFA series): the fixed side carries axial load while the support side accommodates the screw's thermal expansion. Pairing must match the journal diameters at each screw end, so send SYK your screw spec for a matched-set recommendation.

Contact SYK

For LK12 specifications, 2D/3D CAD files, or help confirming lead time and a matched fixed-side/support-side set, contact SYK directly. Share your screw bore, accuracy grade, and operating environment, and the factory will map the correct model and lead time.