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Part finishing under CNC

Part finishing under CNC

Birchwood Casey’s CNC
Birchwood Casey’s CNC system automates the black-oxiding process.

CNC part finishing is now possible on any scale, large or small, without having to add labor. What makes this possible is Birchwood Casey’s TruTemp system that offers the many benefits of automated black-oxide finishing to most shops at no more than the cost of a small machining center, said company vice president Mark Ruhland.

This TruTemp CNC line uses Birchwood Casey’s ( low-temperature non-polluting finishing process along with an integrated programmable hoist and tank line to automatically process iron and steel components with highquality black-oxide finishes.

Designed to eliminate the labor costs associated with manual hoist lines, the system is highly repeatable, eliminates process guesswork and provides high throughput. A standard, 110-gallontank system can process between 4 lb and 6,000 lb per 8-hr shift and can be sized and configured to accommodate any volume of work or production circumstances.

TruTemp system hoists and superstructures handle loads to 500 lb and operate via Allen Bradley PLC digital controls with manual joystick backups. Birchwood Casey extrusion welds the system’s 0.750-in. polypropylene process tanks that have gusset supports under their top rims and perimeter girthing. Setdown saddles automatically center part loads within the tanks.

Tanks can be laid out with pickup and drop-off points at opposite ends of the line or with a single load/unload station with the hoist pickup and dropoff at the same point. System process programs handle as many as three loads concurrently for a maximum throughput of five loads an hour.

The TruTemp CNC hoist processes parts in the following station sequences. Station 1: load and pickup; station 2: alkaline soak clean; station 3-4: double counterflow rinse; station 4: mild acid surface prep; station 5: cold overflow rinse; station 6: TruTemp black oxide; station 7: cold overflow rinse; station 8: rust preventative oil; and station 9: load drop off.

The process cycle takes 28 minutes, and the system produces a satin black magnetite coating measuring 0.5- microns thick, which as no effect on part dimensions or material hardness. The finish withstands as many as 100 to 200 hours of neutral salt spray (ASTM B 117) or several hundred hours of humidity (ASTMD1748) (verified by independent testing). This high level of corrosion protection is important for both part storage and shipment in corrosive atmospheres such as overseas.

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