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National Technologies was commissioned by a customer in the engine manufacturing industry to complete the screw machining of the steel plug highlighted below, for use in an engine assembly. Our advanced single spindle screw machining process was carried out on 12L14 steel utilizing a Brown & Sharpe Ultramatic screw machine. The fine detailing was performed with threading and drilling processes. Deburring was employed for the thorough cleaning of the part, and the unit was finished with a non metallic, corrosion resistant Parco Lubrite 5 manganese phosphate conversion coating. Dimensional and visual inspections were executed to ensure integrity and quality.

The tightest tolerance of ± 0.010” and an angular tolerance of ± 1° were met during fabrication. Overall measurements of the plug were a length of 0.531”, an outside diameter of 0.875”, and a hex dimension of 0.861”/0.880”. After a turnaround time of 2 weeks, 526 plugs were constructed and shipped to the customer as specified. For over 50 years, National Technologies has been providing high volume custom CNC machined and screw machined parts, with an emphasis on customer service. For more about this screw machined plug project or any of our extensive machining capabilities please see the table below or contact us directly.

Single Spindle Screw Machining Project Highlights

Product Name


Product Description

This plug is used in an engine component.

Capabilities Applied/Processes

Single Spindle Screw Machining


Conversion Coating

Equipment Used to Manufacture Part

Brown & Sharpe Ultramatic

Overall Part Dimensions

OD: Ø 0.875″ ± 0.010
Length: 0.531″ ± 0.010
Hex: 0.861″ / 0.880″

Tightest Tolerances

± 0.010″
Angular: ± 1°

Material Used

12L14 Steel

Material Finish

Parco Lubrite 5 Manganese Phosphate Conversion Coated

In Process Testing/Inspection Performed

Dimensional Inspection
Visual Inspection

Industry for Use

Engine Manufacturing



Delivery/Turnaround Time

2 Weeks

Delivery Location

United States

Standards Met

Customer Specifications, 2D CAD Drawing
(SP 9940-503)

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