Steel Custom Parts Manufacturing
Steel is the most widely used material in precision machining. It's strong, cost-effective, and available in hundreds of alloys that can be tailored to nearly any application.
The carbon content in steel (ranging from 0.03–2.1%) along with alloying elements like chromium, nickel, and molybdenum determine how a given grade performs. Low-carbon steels machine quickly and cheaply. Higher-carbon and alloy steels trade some machinability for strength, hardness, and wear resistance. And heat treatment opens up even more flexibility — allowing you to dial in the exact properties your parts require after machining.
We machine millions of steel parts across dozens of alloys. Whether you need free-machining 12L14 for high-volume production runs or heat-treated 4140 for heavy-duty mechanical components, steel gives you the best combination of performance, availability, and value.
A low-carbon steel offering excellent formability and weldability. Its combination of good machinability and ductility makes it ideal for general-purpose components where high strength isn't critical but consistent machining characteristics are essential.
The most commonly used low-carbon steel, providing an optimal balance of strength, machinability, and cost. Its good weldability and uniform properties make it excellent for general-purpose manufacturing where moderate strength is needed.
A medium carbon steel offering increased strength and hardness compared to low-carbon grades. Its ability to be heat treated for improved properties makes it ideal for shafts, pins, and mechanical components requiring good wear resistance.
A re-sulphurized carbon steel engineered for superior machinability. While maintaining good mechanical properties, its enhanced chip formation characteristics make it excellent for high-volume precision components.
A free-machining carbon steel designed for high-speed production. Its optimized composition provides exceptional machinability and surface finish quality, perfect for high-volume automated manufacturing.
An enhanced free-machining steel combining excellent machinability with improved mechanical properties. Its balanced composition makes it ideal for precision parts requiring both good machinability and strength.
The most machinable carbon steel, containing lead for superior chip formation. Its exceptional machining characteristics make it the go-to choice for high-volume, precision-turned components where maximum productivity is crucial.
A chromium-molybdenum alloy steel known for its excellent strength-to-weight ratio. Its superior fatigue resistance and good hardenability make it popular in aerospace and power equipment applications.
A versatile chromium-molybdenum steel with higher carbon content than 4130. Its excellent combination of strength, toughness, and wear resistance makes it ideal for heavily stressed mechanical parts.
A nickel-chromium-molybdenum steel prized for its case hardening properties. Its ability to achieve a hard surface while maintaining a tough core makes it perfect for gears and power transmission components.
A high-carbon chromium bearing steel offering exceptional hardness and wear resistance. Its superior dimensional stability and fatigue resistance make it the standard for precision bearing applications.
An air-hardening tool steel providing excellent dimensional stability and wear resistance. Its good toughness and deep hardening characteristics make it ideal for precision tooling and wear-resistant components.
A tungsten-molybdenum high-speed steel offering excellent red hardness and wear resistance. Its ability to maintain hardness at elevated temperatures makes it perfect for high-performance cutting tools.
A cobalt-enriched high-speed steel providing superior heat and wear resistance compared to M2. Its enhanced hot hardness makes it excellent for demanding cutting applications.
The highest performance cobalt high-speed steel in common use. Its superior hot hardness and wear resistance make it ideal for the most demanding cutting and wear applications where maximum tool life is essential.
Carbon steels, alloy steels, and tool steels form the backbone of precision machined components, each offering distinct advantages for specific applications.
Carbon steels (10xx, 11xx, 12xx series) provide an excellent balance of machinability and strength, with carbon content determining their mechanical properties. Alloy steels (4xxx, 8xxx series) contain additional elements that enhance specific characteristics like hardenability and strength.
Tool steels (A, M series) are engineered for extreme hardness and wear resistance, making them ideal for demanding applications.
Steel alloys provide the essential combination of strength, wear resistance, and durability required in power equipment applications. The material's high fatigue resistance and ability to withstand heavy loads make it ideal for critical mechanical components. Steel's excellent machinability allows for complex geometries while maintaining tight tolerances, and its heat treatment capabilities enable customized hardness profiles for specific wear requirements. These properties, combined with cost-effectiveness, make steel the preferred choice for reliable power transmission and industrial machinery components.
Common Applications:
• Drive shafts (up to 4" diameter)
• Housing components (up to 20" diameter)
• Small to medium bearing housings
• Motor mounting components
• Precision bushings and sleeves
• Coupling components
• Precision hardware and fasteners
Steel alloys deliver the robust performance and durability demanded in agricultural applications. Their superior wear resistance and strength handle the harsh conditions of farming operations, while the material's ability to be heat treated extends component life in abrasive environments. Steel's excellent strength-to-weight ratio enables efficient equipment design, and its cost-effective machining characteristics allow for economical production of complex parts that must withstand heavy use and environmental exposure.
Common Applications:
• Precision mounting components
• Small drive train components
• Hydraulic system fittings and parts
• Bearing housings
• Bushings and wear components
• Control system components
• Precision fasteners and pins
In HVAC and fluid control applications, steel alloys provide reliable performance with excellent value. Their good machinability enables efficient production of complex flow paths and precise geometries, while their strength ensures reliable operation under pressure. Steel's ability to maintain dimensional stability under varying temperatures, combined with its cost-effectiveness for high-volume production, makes it ideal for components that require consistent performance in controlled flow applications.
Common Applications:
• Valve components
• Flow control parts
• High-volume precision fittings
• Mounting brackets and hardware
• Control system components
• Small diameter precision shafts
• Sensor mounting components
With over 75 years of precision machining excellence, we deliver custom steel components that meet the most demanding specifications. From prototype development to multi-million piece orders, our ISO:9001 certified facility specializes in handling complex, high-difficulty work across all steel grades.
Our commitment to quality, combined with extensive machining capabilities, ensures your steel parts and components are manufactured to the highest standards with competitive lead times.
Our advanced vertical and horizontal milling centers (up to 6-axis) excel at machining complex geometries. We reliably produce precision housings, mounting brackets, and critical industrial components for industries like power equipment and HVAC. Count on us for consistent quality across all common steel grades, from low-carbon to high-strength alloys.
Optimize your supply chain for large-quantity orders with our specialized multi-spindle machining. Processing bars up to 1-5/8" and chucking to 6", this service is ideal for consistent, cost-effective production of precision components used in industrial equipment, power systems, and agricultural machinery. We ensure reliable delivery, particularly for free-machining grades like 12L14 and 1215, helping you maintain quality and efficiency.
From precision shaft components to custom parts for industrial braking or HVAC systems, our CNC turning services deliver exceptional accuracy and superior surface finishes. We handle steel bars up to 4" and chucking up to 20" diameter. Partner with Spex for reliable, high-quality turned steel components meeting tight tolerances across all steel grades.
When you need small, highly precise steel components, our Swiss turning capabilities deliver outstanding results. Ideal for instrumentation, control systems, and other high-volume applications requiring tight tolerances on parts up to 7/8" diameter and 4" length. We excel in producing complex, small-diameter parts, especially in free-machining steels, ensuring remarkable accuracy and exceptional surface finishes for your most demanding applications.
Learn more about our machining services and capabilities
Delivering high-quality, consistent steel components is a top priority at Spex. Our quality system is built on our ISO 9001:2015 certification, guiding how we work every step of the way. We carefully check parts during production to ensure dimensional accuracy and address the specific needs of machining steel effectively.
We apply these same quality standards whether we're making a single prototype or thousands of parts. You can be confident in the results, as each project comes with full documentation, including material certifications, detailed measurement reports, and First Article Inspection Reports (FAIRs). This paperwork clearly shows how your parts meet your exact specifications.
We'd love to hear from you!
Scalable production
Short lead times
Fair prices
ISO-9001 certified
Secondary processes
Range of materials
On-time delivery
75+ years in business
Advanced CNC machining
Rapid prototyping
Steel alloys are identified by a 4-digit number assigned by the American Iron & Steel Institute (AISI). The first digit classifies the alloy family: 1XXX is carbon steel, 2XXX is nickel steel, 3XXX is nickel-chromium steel, 4XXX is molybdenum steel, and 5XXX is chromium steel. The second digit indicates the approximate percentage of the primary alloying element. The last two digits indicate the carbon content — so 1018 steel has 0.18% carbon, and 4340 has 0.40% carbon. As an example, AISI 2330 is a nickel steel with roughly 3% nickel and 0.3% carbon. Free-machining variants add a letter — 12L14 means it's a 12XX carbon steel with added lead (L) for improved machinability.
Significantly. Softer low-carbon steels like 1018 and 12L14 machine quickly with good chip control, while higher-carbon and alloy steels like 4140 require slower speeds, different tooling, and more careful feed rates due to their hardness and toughness. Stainless steels introduce their own challenges — particularly work hardening, which demands sharp tooling and consistent engagement. Our machinists adjust parameters for each grade to balance cycle time, tool life, and part quality.
Steel parts can achieve excellent surface finishes when matched with the right tooling, speeds, and feeds for the specific alloy. Free-machining grades like 12L14 produce smooth finishes with minimal effort, while harder alloys may require additional finishing passes. Our Swiss machining capabilities are particularly well-suited for small, intricate parts that demand tight tolerances and fine surface finishes.
Our quality system is built on ISO 9001:2015 certification and applies the same standards whether we're making a single prototype or a multi-million piece production run. We perform in-process dimensional checks throughout production and deliver full documentation with every order — including material certifications, measurement reports, and First Article Inspection Reports (FAIRs).
The more detail, the better. At minimum, we need part drawings or CAD models, the steel grade required (e.g., 1018, 4140, 12L14), tolerances, and quantity. It also helps to know about any secondary operations like heat treating or plating, critical features, and how the part will be used. This lets us recommend the best machining approach and give you a precise quote.
Yes. We coordinate heat treating (hardening, tempering, annealing), plating (zinc, nickel, chromium) for corrosion resistance, powder coating for durable surface finishes, and engraving for part identification. Let us know your full requirements when requesting a quote and we can manage the complete process.
