Drill bit Proline 78055K — metal drill bit Ø 5.5 mm, length 93 mm, 1 pc

Proline 78055K is a single metal drill bit with a diameter of 5.5 mm and an overall length of 93 mm, intended for use with handheld drills and drill presses. Made from high-speed steel with 5% cobalt (HSS-Co), this drill bit is designed for drilling a wide range of metals including steel, aluminium and other ferrous and non-ferrous metals. The 135° point angle with chamfering adjustment supports fast, precise starts and reduces walking when marking and positioning the drill.

Advantages

The HSS with 5% cobalt construction provides elevated heat resistance and wear performance compared with standard HSS, allowing prolonged cutting at higher temperatures. The 135° point angle and chamfering adjustment enable quicker penetration and improved centring on metal surfaces. Manufactured entirely by grinding, the flute geometry and cutting edges offer high accuracy and straightness of holes. Supplied as a single piece in a blister pack, the drill bit is ready for immediate use in professional and hobby metalworking tasks.

Suitable for

• Drilling holes in steel and stainless steel
• Drilling aluminium and other non-ferrous metals
• Use with handheld electric drills and drill presses
• General metalworking and fabrication tasks

Key specifications

• Diameter: 5.5 mm
• Overall length: 93 mm
• Material: HSS with 5% cobalt (HSS-Co)
• Point angle: 135° with chamfering adjustment
• Manufacturing: fully ground for accuracy and straightness
• Suitable for high-alloy, titanium, acid-resistant and creep-resisting steels, cast iron and other difficult-to-machine materials
• Packaging: single piece in blister pack

How to use

Secure the drill bit in the drill chuck, ensuring it is tightened concentrically. Use appropriate cutting speed and feed for the material being drilled; lower speeds are generally recommended for harder alloys and stainless steels. Apply cutting fluid or coolant when drilling heat-sensitive or high-alloy materials to extend tool life and improve chip evacuation. Begin drilling with steady pressure and allow the tool to do the cutting; avoid excessive force that can cause overheating or premature wear.

Usage recommendations

For best results, select speeds and feed rates suitable for HSS-Co tools and the specific metal type. Use cutting fluid for stainless, high-alloy or titanium materials, and periodically withdraw the drill to clear chips when drilling deep holes. Store the drill bit in its blister pack to protect the ground cutting edges until use.