Sunnen SV-310

$150,000 - $250,000 Updated 2026-03-16

Key Specifications

bore diameter range

25 - 200 mm (1 - 7.9 in)

max workpiece height

500 mm (19.7 in)

stroke length

0 - 400 mm (0 - 15.7 in)

spindle speed range

60 - 700 RPM

stroke rate

Up to 60 strokes/min

surface finish achievable

Ra 0.05 - 0.8 µm

Overview

The Sunnen SV-310 is a CNC vertical honing machine from Sunnen Products Company — the St. Louis, Missouri company that has been the global leader in honing technology since 1924. Honing is the precision abrasive finishing process that produces the final bore size, roundness, cylindricity, and surface finish (crosshatch pattern) in engine cylinders, hydraulic cylinders, transmission bores, and precision bearing housings that cannot be achieved by boring, grinding, or reaming alone.

The SV-310 is Sunnen's production vertical honing machine for mid-size bore applications — bore diameters from 25 mm to 200 mm in workpieces up to 500 mm tall. The vertical configuration uses gravity to maintain consistent honing stone pressure against the bore wall throughout the honing stroke, enabling accurate roundness correction and cylindricity control that horizontal honing machines struggle to achieve on deep bores. CNC control of the honing spindle speed, stroke rate, and stone expansion rate enables programmatic control of the honing process — setting the removal rate, the surface finish target, and the final size endpoint — without manual operator gauge checks after each stroke.

Sunnen's proprietary Precision Bore Gauging (PBG) integrates in-process bore measurement directly into the SV-310's CNC control, measuring the bore diameter in real-time during the honing process and automatically controlling the stone expansion to approach the target diameter with the correct finishing behavior. This active gauging eliminates operator-to-operator variability in honing — the same finished bore size and finish is achieved regardless of which operator runs the machine.

At $150,000-$250,000 new, the SV-310 is the production workhorse for automotive engine rebuilders, hydraulic cylinder manufacturers, and transmission builders who require consistent bore quality at production rates that manual honing cannot achieve.

Full Specifications

Parameter	Value
Bore Diameter Range	25 - 200 mm (1 - 7.9 in)
Max Workpiece Height	500 mm (19.7 in)
Stroke Length	0 - 400 mm (0 - 15.7 in)
Spindle Speed Range	60 - 700 RPM
Stroke Rate	Up to 60 strokes/min
Surface Finish Achievable	Ra 0.05 - 0.8 µm
Bore Roundness	< 0.001 mm
In Process Gauging	Active (Sunnen PBG system)
CNC Control	Sunnen SG5 CNC
Machine Weight	~2,200 kg (4,850 lb)

Specifications sourced from sunnen.com — verified 2026-03-28

Strengths & Limitations

Strengths

Active in-process bore gauging (PBG) eliminates operator gauge checks and produces consistent bore size regardless of operator skill
CNC control of spindle speed, stroke rate, and stone expansion provides programmatic control of the honing process
Vertical configuration enables accurate roundness correction in deep bores where horizontal machines lose stone contact uniformity
25-200mm bore diameter range covers automotive cylinder bores, hydraulic cylinders, and most industrial bore applications
Sunnen is the global reference for honing — largest installed base of honing machines worldwide, best parts availability

Limitations

Honing stones are application-specific — correct abrasive specification for each bore material, size, and finish requirement requires Sunnen application engineering support
Honing generates abrasive-laden coolant requiring proper filtration and disposal
Vertical configuration limits maximum workpiece height to 500 mm — longer bores require horizontal honing machines
Honing is a finishing process that requires a pre-machined bore of acceptable size and roundness to start — it does not correct large bore geometry errors

Best For

Automotive engine rebuilders honing engine cylinder bores for passenger car, truck, and performance engine overhaul and remanufacturing Hydraulic cylinder manufacturers producing bore finishes required for tight piston seal fit and low leakage in hydraulic cylinders Automatic transmission remanufacturers honing planetary gear carrier bores and valve body bores to specified size and surface finish Industrial pump and compressor manufacturers honing cylinder bores for reciprocating pump and compressor cylinder assemblies Bearing housing manufacturers producing precision bearing seat bores to H6/H7 tolerance and Ra 0.4 µm or better

Frequently Asked Questions

01 What is honing and how does it differ from grinding?

Honing uses abrasive sticks (honing stones) mounted in an expanding mandrel that rotates and strokes axially inside the bore simultaneously, producing a cross-hatch surface pattern. The stone pressure is maintained against the bore wall by spring or mechanical force, causing the stones to self-sharpen and self-true against the bore. Honing corrects bore geometry errors (out-of-round, taper) while producing the crosshatch surface finish required for oil retention in engine cylinders. Grinding uses a single high-speed abrasive wheel to remove material by abrasion — it's faster for removing large amounts of material but produces a different surface pattern than honing and is used at an earlier stage of bore manufacturing.

02 What surface finish does honing produce?

Honing produces a distinctive crosshatch pattern on the bore surface — a series of intersecting scratch lines at 40-60 degrees to the bore axis. This pattern is intentional: the crosshatch grooves hold lubricating oil at the piston ring interface in engine cylinders, while the flat plateaus between the grooves provide the bearing surface. The SV-310 achieves Ra 0.05-0.8 µm depending on stone grit, spindle speed, and stroke rate. Engine cylinder honing typically targets Ra 0.4-0.8 µm (plateau hone), while precision bearing bores may target Ra 0.1-0.2 µm.

03 How does Sunnen's active gauging work?

Sunnen's Precision Bore Gauging (PBG) system uses an in-bore pneumatic or electronic gauging probe that measures the bore diameter in real-time as the honing spindle strokes. The gauge signal feeds directly to the SV-310's CNC control, which continuously compares the measured bore size to the programmed target size and adjusts the stone expansion rate (and eventually stops stone expansion when target is approached). When the target size is reached, the control signals the spindle to complete a final finishing stroke and retract. This closed-loop control eliminates the traditional operator technique of measuring bore size manually between every few strokes.