The cited comparison lists Nycast 6PA Natural with a tensile strength of 10,000–13,500 psi and a compressive strength of 13,500–16,000 psi [S5].
The comparison is between Nycast 6PA Natural cast nylon and conventional extruded Nylon 6/6, and properties can vary by grade, moisture condition, section size, and manufacturer [S2][S5].
MC901 vs Extruded Nylon: Strength Comparison
Cast nylon is often selected for larger components, heavy sections, and parts requiring extensive machining, while the best choice depends on the part requirements [S2]. Extruded nylon 6/6 is more practical for smaller components machined from standard rod, sheet, and tube [S2].
A direct property comparison is more useful than the labels “cast” and “extruded.” In the cited comparison, Nycast 6PA Natural had a tensile strength of 10,000–13,500 psi versus 11,500 psi for extruded nylon 6/6, and a compressive strength of 13,500–16,000 psi versus 12,500 psi [S5].
Where MC901's Mechanical Advantage Matters
MC901 is described as a preferred choice for large-diameter gears and wheels [S4]. Its higher creep resistance than extruded Nylon 6 GSM makes it especially relevant to large-diameter gears and wheels where sustained loading can distort a part [S4].
The decision depends on load type. MC901 is the preferred candidate for large-diameter gears, wheels, bushings, and heavy wear plates; unfilled extruded nylon remains attractive for smaller gears, spacers, rollers, and stock-driven repeat production [S4]. For a broad material overview, see nylon.
Notched impact testing illustrates the practical advantage: the cited cast grade delivered 0.7–0.9 ft·lbf/in under ASTM D256, compared with 0.6 ft·lbf/in for extruded nylon 6/6 [S5]. That distinction matters where a housing, gear, or wear component may encounter sudden impact rather than steady tensile loading [S3].
Large Parts, Machining, and Dimensional Stability
MC901 is preferable when the design requires a thick or large section, extensive machining, or near-net casting. Polymerization in a mold at low pressure produces a relatively stress-free structure, while extrusion forces molten resin through a die and can leave residual stress that promotes distortion after material removal [S2][S3].
The cited comparison states that cast nylon has lower moisture absorption than extruded nylon, giving it greater dimensional stability [S5]. Moisture-driven dimensional change is therefore a weaker concern in cast material, although both families remain moisture-sensitive [S2][S5].
Extruded nylon offers consistent, readily available rod, sheet, and tube, particularly for smaller sections and thinner gauges [S2]. It is often the lower-friction procurement and production choice when the part does not need MC901’s larger-section capability, impact performance, or improved creep resistance [S2][S4].
Temperature, Wear, and Chemical Exposure Limits
The cited comparison states that cast nylon has a 20-degree higher operating temperature than extruded nylon [S5].
Wear behavior reinforces the selection. Cast nylon is described as more resistant to abrasion and sliding wear than extruded nylon, while filled and internally lubricated grades extend that advantage for demanding tribological service [S2][S6]. Heat, speed, load, lubricant, moisture, and mating-surface roughness still control the actual wear rate, so laboratory comparisons should not be treated as a wear-life guarantee [S3].
MC901 should not be specified from the word “nylon” alone. Confirm the manufacturer grade, filler or lubricant package, conditioning state, and service temperature because additives change strength, stiffness, wear, and moisture behavior [S2][S4]. For environments requiring greater heat resistance or structural rigidity, a different material class may be more appropriate than either nylon option.
Cost, Availability, and Integration Trade-Offs
Cast nylon can be economical for large or complex parts because oversized blanks and near-net shapes reduce machining time and material waste [S2]. It also permits custom colors and specialty formulations for wear or lubricated service [S2]. Extruded nylon usually wins on standardized stock availability and repeat machining economics, particularly when component volume is modest [S2].
Neither process automatically proves cheaper after all manufacturing and failure costs are included. A large MC901 blank may eliminate enough milling time to justify a higher material price, while a small part made from an extruded rod can leave excessive machining waste [S2]. For production planning, compare net-part mass, machining minutes, scrap, fixturing, cycle life, and maintenance exposure rather than purchase price per pound alone [S1][S2].
MC901 is the stronger technical choice for thick, large, impact-prone, wear-loaded, or creep-sensitive parts. Extruded nylon 6/6 is the practical choice for smaller components and standard stock procurement when the service loads remain within its verified limits [S2][S3][S4].
Procurement and Verification Checklist
Specify MC901 by manufacturer and grade, then request the supplier’s current technical data sheet for the exact formulation. The supplied comparison used ASTM D638 for tensile properties, ASTM D695 for compression, ASTM D790 for flexural properties, ASTM D256 for notched Izod impact, ASTM D570 for water absorption, and ASTM D648 for heat-deflection data [S5].
Set acceptance criteria for the same grade, conditioning state, thickness, and machining route, because moisture absorption and section geometry can change the as-machined result [S2][S5]. The source comparison lists a 200–400°F deflection temperature at 264 psi under ASTM D648 for cast nylon and 200°F for extruded nylon 6/6 [S5].
For critical gears, bushings, wheels, or wear pads, require lot-specific strength and wear verification where service risk justifies it. The supporting comparison explicitly advises purchasers to determine suitability through their own testing rather than relying on generic cast-versus-extruded labels [S5].
Track the grade designation, conditioning state, section thickness, and verified wear rate on the drawing or material specification, then revalidate after changing supplier, color formulation, or machining stock size.