Precision Machining Services
Precision grinding, journal polishing, crack detection, and full reconditioning of automotive, heavy-duty diesel, and industrial crankshafts — restored to OEM dimensional specification.
Technical Overview
Our facility provides precision crankshaft grinding and reconditioning services using advanced CNC grinding machines and strict dimensional measurement standards. We restore worn, damaged, or scored crankshafts to manufacturer undersize specifications — ensuring optimal engine performance, correct bearing clearances, and long-term mechanical reliability.
Every crankshaft that enters our workshop undergoes a structured diagnostic sequence before grinding begins. We measure every journal diameter, check for out-of-round, verify straightness, and perform crack detection — providing a complete assessment of the crankshaft's condition before committing to a reconditioning plan.
We do not grind to approximation. OEM specification, dimensional accuracy, and surface finish quality are non-negotiable standards that govern every crankshaft we process — from a 4-cylinder passenger engine to a large-bore industrial diesel.
A crankshaft ground beyond the manufacturer's minimum undersize — or to incorrect roundness — will destroy a set of bearings within hours of engine startup. Precision is not an option. It is the only acceptable standard.
Crankshaft size range: all automotive and commercial diesel platforms. Industrial and large-bore marine crankshafts assessed individually. Contact us with your specifications.
Failure Diagnosis
These are the failure conditions our grinding technicians diagnose and correct. Identifying the correct failure mode drives the appropriate reconditioning path — and prevents misdiagnosis that leads to recurring engine failure.
The most common crankshaft failure — progressive wear of the journal bearing surfaces caused by abrasive contamination in the oil, metal-to-metal contact from insufficient oil pressure, or extended operation beyond service intervals. Journal surfaces develop grooves, scratches, and dimensional loss that destroy bearing films and cause bearing knock.
Journals that have worn unevenly develop an elliptical or out-of-round profile. Even when the mean diameter remains within limits, an out-of-round journal creates a dynamic imbalance that generates vibration, destroys the bearing oil film at one point in every rotation, and causes bearing failure through fatigue spalling and rapid wear.
Extreme localised heat — caused by oil starvation, bearing seizure, or sustained overloading — causes journal surfaces to blue (heat-treat) and harden in an uncontrolled manner. The altered surface metallurgy becomes brittle and prone to micro-cracking. Heat-damaged crankshafts require careful assessment before grinding to verify material integrity remains within limits.
Contaminated oil, foreign object ingestion, or bearing material transfer leaves embedded particles and surface damage on journal bearing surfaces. Even small embedded debris creates localised high-pressure contact points that accelerate journal wear and contaminate fresh bearing shells if the crankshaft is reassembled without grinding and polishing.
Crankshafts can suffer permanent bending from hydraulic lock (water ingestion causing a piston to stop suddenly), dropped valve damage, or severe impact. A bent crankshaft causes vibration, misalignment between main bearing bores, and accelerated wear across the entire bearing train. Straightness is verified before and after grinding on all units we process.
Sudden loss of oil pressure from pump failure, blocked galleries, or low oil level causes metal-to-metal contact at every bearing surface simultaneously. The resulting damage is rapid and severe — typically requiring grinding of all journals. Oil gallery cleaning is essential before reassembly to prevent recurrence from residual sludge or metal particles.
What We Do
Five integrated service categories — every stage executed with precision instrumentation and documented against OEM specification.
The core reconditioning operation — grinding journal bearing surfaces to OEM-specified undersize dimensions with correct roundness, taper, and fillet radius. Performed on CNC crankshaft grinding machines with in-process gauging to maintain dimensional accuracy throughout the grinding cycle.
After grinding, all journal surfaces are polished to achieve the correct surface finish Ra value specified by the bearing manufacturer. Polishing removes the microscopic grinding lay (directional marks) from the journal surface and achieves the smooth, directionally-neutral finish that allows a full hydrodynamic oil film to form at bearing startup.
Comprehensive non-destructive and dimensional inspection conducted before grinding — and on the finished crankshaft prior to despatch. Crankshafts with crack indications that cannot be removed within allowable grind limits are rejected and the client advised before any machining costs are incurred.
Where crankshaft bending is identified and the degree of bend falls within correctable limits, controlled hydraulic press straightening is performed before grinding. Straightening eliminates the root cause of main bearing misalignment — without it, grinding a bent crankshaft to correct individual journal diameters still leaves the engine with an inherent alignment problem.
Our full reconditioning package combines all services into a complete, documented restoration — from receipt through to despatch. Designed for clients who want a single, verified, ready-to-install crankshaft with full measurement traceability and zero ambiguity about the specification it has been ground to.
Workshop Arsenal
Our crankshaft grinding workshop is equipped with purpose-built industrial grinding machines — not repurposed general machining equipment. The difference in achievable dimensional accuracy and surface finish quality is significant, and it directly determines whether a reconditioned crankshaft delivers the bearing life it should.
We have the capacity to handle crankshafts from small 4-cylinder automotive engines through to large-bore heavy diesel and industrial powerplants. Each crankshaft is assessed individually for complexity, and grinding time is allocated to deliver the required dimensional result — not to meet an arbitrary cycle-time target.
Our facility can handle crankshafts from passenger vehicle inline-4 engines through to large commercial truck inline-6 and V8 diesel platforms. Industrial and marine crankshafts are assessed individually. Contact us with your specific crankshaft dimensions and engine type for a capacity confirmation.
Industrial crankshaft grinder with automatic in-process gauging — maintaining dimensional accuracy throughout the grinding cycle without interruption for manual measurement.
Journal size range: 30–120mm diameterBelt-polishing unit designed specifically for crankshaft journal finishing — achieving Ra 0.2–0.4µm surface quality required for hydrodynamic bearing operation.
Achieves Ra: 0.2 – 0.4 µmElectromagnetic crack detection system revealing surface and subsurface cracks at fillet radii and oil galleries — the critical failure-prone zones on any crankshaft.
Detects cracks from 0.1mmCalibrated digital micrometers to 0.001mm resolution — used for pre-grind, in-process, and post-grind journal diameter measurement at multiple positions and planes.
Resolution: 0.001mmPrecision V-block runout measurement equipment for crankshaft straightness assessment and post-straightening alignment verification.
Runout measurement: 0.001mmContact profilometer measures and records Ra surface roughness on finished journal surfaces — providing objective, traceable confirmation of surface finish specification compliance.
Ra range: 0.05 – 10 µmEngine Coverage
Our crankshaft grinding capability covers the full spectrum of engine types operating across Nigeria's automotive, commercial, and industrial sectors — from passenger car petrol engines to large-displacement industrial diesel powerplants.
Petrol and diesel car engines — 4-cylinder, inline-6, V6, and V8 configurations. All major Japanese, European, and Korean platforms commonly operating in Nigeria.
Heavy transport diesel engines — inline-6 and V8 configurations with larger journal diameters and higher crankshaft mass. Handled with appropriate fixturing.
Excavator, bulldozer, crane, and loader diesel engines — Komatsu, CAT, Volvo, and Liebherr platforms frequently requiring crankshaft reconditioning after extended field operation.
Standby and prime power generator set engines — Perkins, Cummins, and Caterpillar platforms widely used across Nigeria for commercial and industrial power generation.
Propulsion and auxiliary engine crankshafts for inshore and offshore vessels. Assessed individually based on dimensions and platform — contact us with specifications.
Large-bore mining haul truck and industrial plant diesel crankshafts — including Komatsu and Liebherr mining equipment engine platforms.
Engineered Workflow
Every crankshaft processed in our facility follows this structured workflow without exception. Each stage is a quality gate — no crankshaft progresses to the next step until the previous one is completed and verified.
Receipt inspection and complete dimensional survey — all journal diameters measured in two planes at two positions. Out-of-round, taper, and journal runout recorded. Grind plan determined.
Survey ReportMagnetic particle inspection of all fillet radii and oil gallery entrances. Crankshaft supported on V-blocks for main journal runout measurement. Pass/fail issued before machining costs incurred.
NDT GateCNC crankshaft grinding to the confirmed undersize — mains first, then rod journals. In-process gauging maintains dimensional accuracy. Fillet radii generated per OEM drawing.
Core ProcessBelt polishing of all ground journals to Ra 0.2–0.4µm finish. Oil gallery edges chamfered and deburred. Surface roughness measured and recorded on every journal with profilometer.
Finish StageAll journals re-measured post-polish in two planes at two positions. Roundness, taper, and final diameter recorded. Any journal not meeting specification reground before QC sign-off.
QC GateComplete crankshaft grinding report issued — all pre- and post-grind dimensions, undersize ground, surface finish results, and inspector sign-off. Crankshaft cleaned, oiled, and protected for despatch.
DocumentationEngineering Standards
Our crankshaft grinding standards are not internal targets — they are derived directly from engine manufacturer service manuals, bearing manufacturer technical specifications, and established precision machining practice for the engine type being processed.
Tolerance compliance is not checked once at the end of grinding. It is verified progressively throughout the process — ensuring that no dimensional deviation is allowed to compound before it is corrected.
| Parameter | Standard | Significance |
|---|---|---|
| Journal roundness (out-of-round) | Max 0.025mm | Prevents cyclic bearing load failure |
| Journal taper per journal | Max 0.025mm | Prevents edge loading on bearing shells |
| Surface finish — Ra value | 0.2 – 0.4 µm | Required for hydrodynamic oil film |
| Undersize increment grinding | ±0.005mm | Correct bearing clearance maintained |
| Fillet radius accuracy | Per OEM drawing | Controls fatigue failure at stress point |
| Crankshaft runout (straightness) | Per OEM limit | Ensures main bearing alignment |
We grind only to the manufacturer's defined undersize increments — ensuring that correct oversized bearing shells produce the specified oil clearance when installed. Custom grinds beyond published undersizes are not performed without specific engineering assessment.
Roundness control is the most critical quality parameter in crankshaft grinding. Our CNC grinder's in-process gauging maintains roundness throughout the grinding cycle — not just at the end. An out-of-round journal is never acceptable, regardless of correct mean diameter.
Surface finish Ra is measured on every journal with our profilometer — not estimated from visual inspection. A journal that looks smooth to the eye may still be outside the Ra 0.4µm upper limit for bearing shell compatibility. We do not rely on visual assessment alone.
The final purpose of all crankshaft grinding is to produce the correct running clearance between journal and bearing shell at the correct oil temperature. We provide clients with the ground undersize and the bearing part number required to achieve OEM clearance — taking the guesswork out of reassembly.
Proven Results
A construction firm operating heavy earthmoving equipment in the Niger Delta region presented 8 Caterpillar C15 diesel engine crankshafts following simultaneous multi-machine oil pressure failures triggered by contaminated fuel-system-related sludge blocking oil galleries. All 8 crankshafts showed severe journal scoring on mains and rod journals. Two units showed additional bending from hydraulic lock events. The client required all 8 units returned at the same undersize to allow standardised bearing stock — a significant coordination requirement in a multi-crankshaft batch of this type.
All 8 crankshafts processed through full reconditioning — complete oil gallery flush and cleaning, magnetic particle inspection, two units straightened before grinding, then all 8 ground to 0.020" undersize on all journals. Post-grind roundness and taper verified on every journal of every crankshaft. Full polishing and profilometer verification. Complete QC documentation issued for each unit with before-and-after measurement records. All 8 returned within 14 working days on a staggered schedule matching the client's engine rebuild programme.
All 8 engines rebuilt and returned to active site duty. Zero bearing failures reported across the fleet in the 18 months following reconditioning. Client reports fuel efficiency and power output restored to pre-failure levels on all machines. Estimated cost saving versus replacement crankshafts: approximately 65% per unit across the fleet.
The AutoBore Difference
We operate purpose-built CNC crankshaft grinding machines — not converted general grinding equipment. The difference is dimensional accuracy, repeatability, and in-process gauging capability that general machinery cannot provide. Industrial equipment produces industrial results.
Every dimensional parameter is measured with calibrated instrumentation, recorded, and verified against specification. We issue a grinding report with every crankshaft — providing complete traceability of what was ground, to what dimension, and what the measured result was. No guesswork.
Crankshaft grinding is a skilled machining operation that requires judgement beyond machine settings — understanding how heat, grinding wheel wear, and workpiece deflection affect dimensional outcomes. Our technicians bring years of crankshaft-specific experience to every job.
Multi-crankshaft batch processing with dedicated workshop scheduling allows fleet operators to plan engine rebuild programmes around confirmed return dates. We understand that a crankshaft in our workshop means an engine waiting for rebuild — and we prioritise accordingly.
When a crankshaft requires grinding as part of a full engine rebuild, our engine rebuilding team handles the complete overhaul — cylinder head reconditioning, piston and ring fitting, and precision assembly. One facility, one programme, one accountable engineering team for the entire engine.
Ready to Get Started
Our engineering team is ready to assess your crankshaft, confirm the reconditioning scope, and provide a fast, accurate quotation. Single units and fleet batches welcome.