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NC Spot Drills
Wide range of spotting drills available in HSS or solid carbide.
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Browse by Type
90°
NC Spot Drills
Wide range of 90° spot drills available in HSS or Carbide, coated or uncoated
120°
NC Spot Drills
Wide range of 120° spot drills available in HSS or Carbide, coated or uncoated
Browse by Coating
What are NC spot drills and when would I use them?
Spot drills, commonly known as NC spot drills, are mainly used to drill an accurately positioned indention on a workpiece surface. The indentation acts as a guide and a reference point for non-self-centring drills. Using a spot drill will improve the overall accuracy of the finished hole. The design and substrate of NC spot drills vary, however typically feature a 90°, 120° or 142° drill point angle and are manufactured from HSS or carbide.
Why does the tip angle matter when using NC spot drills?
When choosing a spot drill, it is important to select the correct drill point angle. This is key to achieving and maintaining the highest accuracy. The chosen point angle determines the contact area and depth of the initial indentation or spot, also serving as a precise reference point for the drilling operation. Using the correct point angle ensures that the centre of the drill bit makes the first contact with the workpiece, reducing the risk of chipping the cutting edge and eliminates risk of deviations and improve overall precision.
HSS vs carbide NC spot drills
Like many cutting tools, spot drills are available in HSS (high speed steel) and carbide, both having different benefits:
High-Speed Steel (HSS) Spot Drills
Advantages:
- Cost-efficiency - Generally more affordable than carbide, making them a budget-friendly option.
- Toughness - Offers better toughness and can withstand vibrations, making them suitable for less rigid set ups.
Disadvantages:
- Hardness - Lower hardness versus carbide, potentially leading to shorter tool life in certain applications.
- Speed and feed rates - Limited compared to carbide, affecting efficiency in high-speed machining.
Carbide Spot Drills
Advantages:
- Hardness - Carbide is significantly harder than HSS, providing extended tool life and better wear resistance when machining difficult materials.
- High speed machining – Better suited for high-speed operations, improving overall machining efficiency.
- Heat resistance - Carbide excels in high-temperature environments, maintaining hardness at elevated cutting speeds.
Disadvantages:
- Cost - Generally more expensive than HSS, making them a higher upfront investment.
- Brittle - Carbide is more brittle than HSS, making it prone to chipping or breakage in unstable conditions.
What materials can you use NC spot drills on?
NC spot drills can be used on various materials, with the exact material-set dependent on the spot drill substrate and coating. HSS (high speed steel) spot drills can be used on mild steel, alloy steel, tool steel, cast iron, non-ferrous metals and plastics. It's important to note that while HSS is a versatile material, it may not be the best choice for extremely hard or abrasive materials. Carbide spot drills are better suited to drilling difficult to cut metals like stainless steel, titanium, steel up to 50 Rockwell and abrasive non-ferrous metals. Having a coating on the spot drill will improve tool life and help protect against heat build-up, whereas uncoated spot drills are better suited to drilling plastics and sticky materials like aluminium. Not having a coating prevents material build up on the cutting edge.
What do I need to consider when choosing the right spot drill?
When selecting a spot drill for your application, it's important to consider several key factors to ensure optimal performance:
- The first thing to consider is the material you'll be working with, as different spot drills are designed for specific materials such as mild steel, alloy steels, cast iron, stainless steel and non-ferrous metals.
- Finished hole size is the next factor to consider as spot drills come in various sizes and with different drill point angles.
- The type of coating should also be considered, with options like TiN and TiAlN offering enhanced durability and heat resistance.