High-Strength CNC Machined Alloy Steel Connecting Rod
High-strength CNC machined alloy steel connecting rods produced from forged or billet alloy steel blanks with precision-machined bores, split faces, bolt seats, and bushing pockets for engine, compressor, pump, and industrial machinery applications. 4140, 4340, and 8620 grades with controlled heat treatment, shot peening, and 100% crack detection. Center-to-center distance up to 800 mm, dynamic balancing to G2.5.
Manufacturing Processes :
CNC turning (multi-axis with live tooling), CNC milling (3/4/5-axis), cylindrical grinding, centerless grinding, honing, thread cutting, broaching, drilling & tapping, EDM wire-cut (partner)Heat Treatment :
Quench & temper | Case hardening / carburizing | Induction hardening | Solution annealing | Vacuum hardening | Nitriding | Stress relieving. Every heat treatment batch ships with time–temperature chart and hardness report.Surface Treatment :
Zinc plating (clear/yellow passivation) | Zinc-nickel alloy | Electroless nickel | Hard chrome plating | Black oxide | Phosphating (MnPO4) | Passivation (ASTM A967) | Electropolishing | Anodizing (aluminum) | Powder coatingCustomizable :
YesOrder(MOQ) :
Prototype: 1–10 pcs (no MOQ for billet-machined parts). Small batch: 10–500 pcs. Series production: 500–50,000+ pcs/month.Specifications
Shengtao's high-strength CNC machined alloy steel connecting rods are manufactured through a disciplined production sequence that begins with forged or billet alloy steel blanks, proceeds through rough machining in the annealed condition to establish the basic geometry of the beam, big-end bore, small-end bore, and bolt seats, and continues through a controlled heat treatment cycle that develops the specified strength and toughness before finish machining brings every feature to final tolerance. The sequence is designed so that the bores are rough-machined with a grinding or honing allowance, the rod is heat-treated, the split faces are ground flat and mated, the bolt holes are drilled and tapped, and the bores are then finished to H7 tolerance by precision boring or honing — in that order — ensuring that the finished bore is round, cylindrically true, and correctly positioned relative to the split face and bolt seats regardless of any minor distortion during heat treatment.
Alloy steel is the universal material for connecting rods because the combination of high tensile strength, fatigue resistance, and toughness cannot be matched by plain carbon steel. 4140 (42CrMo4) is the most widely specified grade: after quench and temper to 28–40 HRC it provides an excellent balance of strength and ductility for rods in industrial compressors, pumps, and medium-speed engines. 4340 (34CrNiMo6) is selected for large-bore, high-output engines and heavy machinery where higher hardenability ensures uniform properties through the full cross-section. For connecting rods that must combine a hard, wear-resistant bore surface with a fatigue-resistant core — such as high-speed compressor rods and high-performance automotive conrods — 8620 (20CrMnTi) is case-carburized to 58–62 HRC at the surface while the core remains tough and ductile.
Every connecting rod undergoes 100% crack detection by magnetic particle inspection (MPI) after finish machining to confirm freedom from surface or near-surface defects. Dimensional inspection on CMM verifies center-to-center distance, bore diameter and roundness, bolt seat flatness, and split face flatness against the drawing. Where specified, the rod is shot-peened to introduce compressive residual stress in the surface, which significantly improves fatigue life by inhibiting crack initiation. Dynamic balancing to G6.3 or G2.5 is available for rods that will operate in high-speed rotating assemblies. Contact us with your connecting rod drawing for a quotation within 24 hours.
High-Strength CNC Machined Alloy Steel Connecting Rod is one of our core strength products. We maintain substantial inventory to ensure rapid delivery and can also customize extra-large diameter seamless pipes according to your specific requirements. Additionally, we provide comprehensive services including spectroscopic analysis, mechanical property testing, pressure testing, and non-destructive testing (NDT).
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Note: If you do not find a High-Strength CNC Machined Alloy Steel Connecting Rod that meets your requirements or is suitable for your customer’s project, please contact our manager sales consultant (Email: stsalesman4@stmetal001.com) and send us your specifications and technical parameter files to obtain Customized quotation plan. |
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FAQs
Q: What machined parts and fabrication services does Shengtao provide?
Shengtao is a China-based, ISO 9001-certified one-stop manufacturer delivering precision-machined and fabricated metal parts across 10 product categories:
• CNC Precision Machined Parts — turned, milled, and 5-axis complex components
• Stamped & Formed Metal Parts — progressive die stamping, deep drawing, sheet metal fabrication
• Welded & Fabricated Steel Assemblies — structural weldments, pressure vessel shells, pipe spools
• Hydraulic & Pneumatic Components — honed cylinder barrels, chrome-plated piston rods, valve bodies
• Automotive Precision Parts — drivetrain, suspension, steering, and engine components
• Surface-Treated Steel Parts — mirror polishing, electropolishing, hard chrome, zinc/nickel plating
• Precision Tube & Pipe Machined Parts — tube end machining, honing, pipe spool assemblies
• Laser Cut & Waterjet Cut Parts — precision 2D profiles up to 150 mm thick
• Machined Pipe & Tube Fittings — threaded fittings, forged flanges, custom connectors
• Special Alloy & High-Performance Parts — Inconel, Hastelloy, Titanium, tool steel components
We work from your drawings, providing customized parts — we do not sell standardized off-the-shelf items. Send your RFQ with a drawing to start a quotation.
Q: Can you manufacture custom parts from my engineering drawings? What file formats do you accept?
A: Yes — custom manufacturing to your drawings is our core business. We accept:
• 2D drawings: PDF, DWG, DXF
• 3D models: STEP (.stp), IGES (.igs), SolidWorks (.SLDPRT / .SLDASM), CATIA, Inventor
The process is straightforward:
1. Send your drawing/model with material specification, quantity, and any special requirements.
2. We sign an NDA before reviewing your files.
3. Our engineering team performs a DFM (Design for Manufacturability) review and flags any concerns.
4. We send a formal quotation with price, lead time, and technical notes within 24–48 hours.
We handle everything from raw material sourcing through machining, heat treatment, surface finishing, inspection, and export packaging — delivering parts ready for your assembly line.
Q: What materials can you source and machine for my parts?
A: We source and machine a comprehensive range of metals, all with certified mill test reports (MTR):
Stainless steel: 303, 304, 316, 316L, 321, 410, 420, 430, 2205, 2507 (duplex/super duplex)
Carbon steel: A36, 1020, 1045, A105, A106 Gr.B, API 5L X42–X80, S235, S355
Alloy steel: 4140, 4340, 8620, 42CrMo4, 34CrNiMo6, 20CrMnTi, A387 Gr.11/22
Aluminum: 6061-T6, 7075-T6, 5052, 5083
Tool steel: D2, H13, M2, P20, S7
Nickel alloys: Inconel 600/601/625/718, Hastelloy C-276/C-22, Monel 400
Titanium: Grade 1, Grade 2, Grade 5 (Ti-6Al-4V), Grade 23 (Ti-6Al-4V ELI)
Brass & copper: C36000, C11000, C26000
If your specification calls for a material not listed above, please ask — we work with approved steel mills and can source commercial grades, pressure-vessel grades, and AMS/aerospace grades.
Q: Do you offer welding and fabrication for complex assemblies, including code-compliant work?
A: Yes. Welding and fabrication is a core Shengtao capability, covering single-part weldments through to fully welded structural frames, pressure vessel shells, and pipe spools.
Welding processes: SMAW, GMAW/MIG, GTAW/TIG, SAW (submerged arc), FCAW, orbital TIG
Welder qualifications: AWS D1.1 / D1.6, ASME Section IX, EN ISO 9606
NDE capabilities: 100% VT, PT, MT, UT, RT (X-ray) available, including third-party witness
We fabricate to:
• ASME Section VIII Div.1 — pressure vessels
• ASME B31.1 / B31.3 / B31.4 — power, process, and liquid piping
• AWS D1.1 — structural steel
• PED 2014/68/EU — European pressure equipment
• NACE MR0175 / ISO 15156 — sour service
Every fabrication ships with a full data book: weld map, WPS/PQR, welder qualifications, NDE reports, MTRs, dimensional inspection, and hydrostatic test certificate.
Q: Do you offer engineering support or design feedback on my part drawings?
A: Yes, and we encourage it. Our in-house engineering team reviews every drawing before production and provides DFM (Design for Manufacturability) feedback at no cost:
We check for:
• Machinability: features that are difficult or impossible to produce (e.g., sharp internal corners, unreachable undercuts, extreme aspect ratios)
• Tolerance optimization: identifying dimensions where looser tolerances can reduce cost without affecting function
• Material alternatives: suggesting equivalent grades if the specified material has long lead times or is cost-prohibitive
• Cost reduction opportunities: changes that simplify fixturing, reduce setups, or allow more efficient tooling
This is a value-added service at no extra charge — many customers have reduced per-part cost by 15–30% through DFM suggestions while maintaining full functionality.
We never modify your drawing without your written approval. All DFM suggestions are clearly annotated on a marked-up drawing for your review.
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Note: If you do not find a High-Strength CNC Machined Alloy Steel Connecting Rod that meets your requirements or is suitable for your customer’s project, please contact our manager sales consultant (Email: stsalesman4@stmetal001.com) and send us your specifications and technical parameter files to obtain Customized quotation plan. |
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