Description

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C7 Ball Screws provide accurate linear motion for standard positioning applications and factory automation. Featuring a cumulative lead tolerance of ±0.050 mm per 300 mm travel, these cold-rolled screw shafts combine with SFU flanged single nuts to deliver stable drive efficiency, uniform axial rigidity, and low friction across high-cycle duty runs.

Key Features

01/

C7 Pitch Accuracy Complies with ISO 3408-3 and JIS B 2051 standards, maintaining cumulative lead variation within ±0.050 mm over 300 mm.

02/

Induction-Hardened Steel Threaded shafts are induction hardened to HRC 58–62, preserving core toughness while reducing dynamic surface wear.

03/

SFU Internal Circulation Nut Flanged single nut utilizes internal steel ball return tracks, reducing outer dimensions for compact machine installation.

04/

Standardized End Machining Journal ends are precision turned and ground to fit standard BK/BF and FK/FF support bearings.

Technical Specifications

Parameter	Specification	Standard / Unit
Accuracy Grade	C7 Grade	±0.050 mm / 300 mm
Process Type	Cold Thread Rolling	ISO 3408 Class 7
Shaft Material	S55C Carbon Steel	Case Hardened
Nut Material	20CrMo Alloy Steel	Carburized
Hardness Depth	HRC 58 – 62	Effective depth 1.5–3.0 mm
Ball Material	GCr15 Chrome Steel	Precision Grade 10
Axial Clearance	≤ 0.050 mm	Non-preloaded standard
Straightness	≤ 0.080 mm / 1000 mm	Dial indicator verified
Temperature	-20 to +80	°C

Product Configuration

SFU 16 05 T 4 D - C7 - 1000 - P0

Nut Style	SFU (Single Nut with Oval Mounting Flange)
Shaft Diameter	16 mm nominal
Screw Lead	05 mm pitch
Thread Hand	T (Right-Hand Thread)
Circuit Count	4 Ball Return Turns
Flange Style	D (Double-Flat Cut Flange)
Tolerance Class	C7 Grade
Total Length	Overall length in millimeters
Preload Class	P0 (Standard axial clearance)

Accuracy & Lead Specifications

Tolerance Grade	Lead Error (e300)	Axial Play	Manufacturing Method
C7	±0.050 mm / 300 mm	≤ 0.050 mm	Cold Thread Rolling
C5	±0.018 mm / 300 mm	≤ 0.020 mm	Precision Rolling / Grinding
C3	±0.008 mm / 300 mm	≤ 0.005 mm	Thread Grinding

Preload & Axial Play

P0 Clearance Standard Zero internal preload with controlled axial clearance up to 0.050 mm. Lowers input drive torque and heat generation in horizontal drive units.

P1 Light Preload Option Selective ball sizing eliminates internal radial clearance. Reduces axial backlash to ≤ 0.015 mm while maintaining steady rotational efficiency.

Dimensions & Selection Matrix

Model	Dia. (d) (mm)	Lead (P) (mm)	Ball (Dw) (mm)	Dynamic Load Ca (kgf)	Static Load C0a (kgf)	Nut Dia. (D) (mm)	Flange (A) (mm)	Nut Length (L) (mm)
SFU1204	12	4	2.381	620	1150	22	42	35
SFU1605	16	5	3.175	1380	3050	28	48	42
SFU1610	16	10	3.175	1320	2880	28	48	42
SFU2005	20	5	3.175	1550	3880	36	58	42
SFU2505	25	5	3.175	1720	4900	40	62	42
SFU2510	25	10	4.762	2980	7350	40	62	60
SFU3205	32	5	3.175	1950	6500	50	80	42
SFU3210	32	10	6.350	4800	12100	50	80	66
SFU4010	40	10	6.350	5450	15200	63	93	66

Manufacturing Process

• Raw Material Inspection Chemical composition and tensile testing of S55C steel bars.
• Centerless Grinding Outer diameter turned to exact pre-rolling shaft dimensions.
• Precision Thread Rolling Cold rolling dies form thread profiles under dynamic pressure control.
• Induction Hardening High-frequency heating generates a 1.5–3.0 mm hardened layer across threads.

• Straightening & Calibration Hydraulic presses adjust total runout to within 0.080 mm / 1000 mm.
• CNC Journal Machining End steps, keyways, snap-ring slots, and thread seats machined to print.
• Assembly & Quality Inspection Ball loading, lead error inspection via laser interferometer, and axial clearance verification.

Applications of C7 Ball Screws

Cartesian Automation Drives linear motion axes in pick-and-place modules and material transfer gantries.
Engraving Machinery Translates rotational motion into linear feed on primary positioning axes.
Laser Cutting Auxiliaries Controls height adjusters, focus positioning units, and loading tables.
Packaging Machinery Executes linear pushing, indexing, and sorting functions under continuous operational runs.

Manufacturing Verification

Laser Interferometer Verification Pitch accuracy verified across total thread length to confirm C7 tolerance compliance.
Concentricity Control Journal grinding keeps end-step runout within 0.015 mm relative to shaft center lines.
Material Traceability Raw material melt certificates and hardness inspection reports supplied with orders.

Customization Options

Shaft Lengths Continuous thread rolling lengths available up to 6000 mm.
Journal Profiles Custom end steps produced according to engineering prints, including internal threads, keyways, and drive flats.
Surface Coatings Black oxide or hard chrome plating available for elevated humidity environments.

CAD Drawings & Datasheets

2D Drawings PDF and DXF dimensional drawings featuring standard SFU nuts and BK/BF support units.
3D CAD Models STEP and IGES files formatted for assembly integration and clearance verification.
Technical Datasheets PDF documentation including critical speed limits, buckling load calculations, and mounting procedures.

FAQ

Q: How is C7 lead accuracy measured during production?

A: Lead error is inspected using a laser interferometer across the full threaded length, ensuring total pitch deviation remains within ±0.050 mm per 300 mm segment.

Q: What end machining options are offered?

A: Shaft ends are machined to fit standard support bearing units or customized according to specific engineering drawings.

Q: What is the standard maximum shaft length?

A: Continuous rolled shafts can be produced up to 6000 mm, with total straightness held within 0.080 mm per 1000 mm.

Q: What lubricant is recommended for standard operation?

A: Lithium-soap grease is standard for operating speeds up to 3000 RPM. ISO VG 32 to 68 oil lubrication is suggested for continuous movement cycles.

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