Precision Parts and Mold Manufacturing for the Machinery Industry

In machinery manufacturing, the load a part will carry, its operating speed, and its wear and corrosion conditions determine material selection. Materials commonly used for CNC-machined metal parts and molded plastic parts include:

• Carbon and alloy steels: S235/S355 for frames and connecting parts; C45 for shafts and flanges; quenched and tempered 42CrMo4 for high-strength shafts; case-hardened 16MnCr5 for gears and pins.
• Stainless steels: 1.4301 (AISI 304) and 1.4404 (AISI 316L); corrosion resistance in food processing and agricultural machinery.
• Aluminium alloys: 6082 and 7075; lightweight housings, holders and fixtures.
• Brass and bronze: Bushings, bearings and sliding surfaces.
• Engineering plastics: POM and PA6 GF30 for gears, rollers and guide parts; PE-UHMW for wear plates.

If secondary operations such as heat treatment, coating (galvanizing, nickel plating, anodizing) or grinding are required, they are included in the production plan from the start. For plastic part molds, hardened 1.2343 mold steel is preferred for high volumes and glass fiber reinforcement, and pre-hardened 1.2311 for medium volumes.

For machine parts, the question "mold or machining?" is answered by annual volume and part geometry. A part that is CNC machined at low volumes can be produced far more economically with a plastic or aluminium injection mold as volumes increase. During this transition, we revisit the design:

• DFM and conversion design: Solid sections designed for machining are converted into uniform wall thicknesses, ribs and draft angles suitable for molding.
• Metal insert molding: Metal hubs, bushings or threaded inserts are embedded in plastic gears and rollers to increase strength.
• Plastic gears: Shrinkage is accounted for along the tooth profile; hub and tooth areas are cooled evenly.
• Threaded parts: Mold designs with unscrewing mechanisms or collapsible cores are evaluated for internally and externally threaded parts.
• Aluminium injection: Machining allowance is left on precision areas such as bearing seats and mounting holes for post-casting machining.

All design decisions are shared with our customer on the 3D model, and steel cutting does not begin until approval is received.

For machine parts, surface quality is often more about function than appearance: sealing, friction, wear and assembly fit. Surface requirements should therefore be defined individually on the drawing according to the part's function.

• Machined surfaces: Typical values are Ra 3.2 µm for general machined surfaces, Ra 0.8–1.6 µm for bearing and seal surfaces, and Ra 0.4 µm or below for ground surfaces.
• Molded plastic parts: For functional machine parts, an EDM finish in the VDI 3400 24–30 range or an SPI B–C finish is generally sufficient; lower roughness may be required on sliding surfaces.
• Aluminium die-cast parts: The as-cast surface must be suitable for shot blasting, anodizing or pre-paint preparation. The polish level of the mold surface directly affects part release and the cast surface.
• Edges and burrs: On machined parts, deburring and chamfering are standard operations for safe assembly.

When surface roughness is specified on the drawing as values measurable with a profilometer, the acceptance criterion becomes clear and differences in interpretation between suppliers are eliminated.

In machinery manufacturing, tolerances determine how parts fit together. For CNC-machined parts, general tolerances are mostly defined per ISO 2768 and shaft-hole fits per ISO 286; for molded plastic parts, ISO 20457 tolerance groups are used.

In plastic parts, moisture absorption (especially in PA6) and temperature changes affect dimensions; measurement conditions (conditioning time, ambient temperature) should therefore be specified on the drawing. For shafts and flanges, geometric tolerances (ISO 1101) such as runout, coaxiality and perpendicularity are often more critical than dimensional tolerances. In assemblies where molded plastic parts work together with metal parts, the tolerance stack-up is calculated as a whole.

Machinery manufacturing is the field in which CNC machining is used most intensively. From prototypes to series parts, we produce in a wide range of quantities in exact accordance with technical drawings:

• CNC turning: Shafts, bushings, flanges, pins and gear blanks; OD and ID turning, grooving and threading.
• CNC vertical machining center: Pocketing, drilling and contouring on housings, brackets, mounting plates and fixture components.
• Wire and sinker EDM: Keyways, narrow slots and precision profiles in hardened parts.
• Surface grinding: Plates and wear parts that require flatness and parallelism.

The precision discipline of mold making is also an advantage when machining machine parts: toolpaths are simulated using the same CAD-CAM infrastructure, and collisions and machining errors are eliminated before they reach the machine. In contract production of semi-finished parts, deliveries follow a batch schedule aligned with the customer's assembly plan. Our proximity to Konya's strong machinery and agricultural machinery industry also enables fast sampling and short lead times.

For machine parts, trial and approval take two forms: T0/T1 trial shots for molded production, and first article approval for CNC-machined parts.

• Molded parts: In the T0 trial, filling, ejection and insert placement are checked; T1 samples are submitted for approval with a dimensional report. Plastic gears are also tested functionally in assembly for tooth profile and runout.
• First article inspection (FAI): Before series CNC production, the first part is checked against all dimensions and geometric tolerances on the drawing.
• Process record: Once approved, injection parameters or CNC tooling and cutting data are recorded; repeat orders are produced with the same settings.
• Prototypes and small batches: Before investing in a mold, assembly and functional tests can be carried out with CNC-machined prototypes.

The approved sample is retained as a comparison reference throughout series production; first article approval is renewed whenever the material or process changes.

In machinery manufacturing, quality means documenting the right dimensions, the right material and proper assembly fit.

• Measurement: In-process and final inspection are carried out with calipers, micrometers, dial indicators and gauges (plug, ring and thread gauges); CMM measurement is common industry practice for complex geometries and is included in the inspection plan when required.
• Material certificates: EN 10204 3.1 material certificates can be requested for steel and aluminium raw materials and are tracked by batch.
• Heat treatment and coating records: Hardness test results and coating certificates are added to the order file.
• Traceability: Raw material, machining and inspection records are linked through the batch number.

Dimensional reports and shipping documents are prepared in line with the supplier requirements of customers with ISO 9001-based quality requirements. In the event of a nonconformity, root cause analysis is performed and a corrective action plan is shared with the customer. For repeat orders, previous inspection reports are used as a reference to monitor batch-to-batch variation.