Deep hole drilling process
ELB drilling is the appropriate method for a range of drilling diameters and depths, including extremely deep holes and small diameter holes. Larger holes may be achieved most effectively with BTA drilling methods.
ELB versus BTA drilling
ELB drilling differs from BTA drilling due to the high pressure oil entry and chip removal. ELB drills introduce high pressure oil through a small hole within the tool, and chip removal occurs through a groove outside the tool.
BTA drilling has an oil enter through a mechanism around the tool, while chips are evacuated through the drill itself. BTA drilling becomes more effective than ELB drilling around a 30 mm hole diameter.
Deep hole drilling machine
Specifically designed to provide the optimum conditions for operating the ELB drill, the deep hole drilling machine is equipped with a high pressure pump that delivers lubricant to the rear of the drill. The drill can be driven by the spindle or held stationary if the workpiece is being rotated. During drilling, advancement can either be by drill or workpiece movement.
A typical ELB drill consists of three parts: a carbide tip, a heat treated alloy shank, and a steel driver. All are typically silver brazed together, and are designed to allow coolant to pass through its entire length. The shank must be properly formed, heat treated, and aligned to absorb cutting torque, sagging, and the whipping associated with high RPM’s.
The drill is positioned and held in the spindle nose, then guided into the workpiece through a pre-started hole or guide bushing that prevents vibration and ensures accuracy. Deep hole drill cutting edges form thin, curled chips that are carried away from the bore by high pressure oil. The off-center design of the cutting edges creates pressure within the bore that is carried by pads behind the drill tip. The coolant that flushes the chips also lubricates these pads, which burnish the surface and develop the fine finish for which deep hole drilling is known.
Cost effective solution
Deep hole drilling is a very cost effective solution for integrated cooling systems, integrated electrics-and data communication wiring, integrated pneumatics and hydraulics.
On itself, deep hole drilling is competing with external hydraulic, pneumatic hoses that are faced with hard conditions and wear. Over life time, deep hole drilling solutions are more reliable and more cost effective.
It’s of upmost importance to make sure that the design is prepared for the process. For more information see our Design rules for Deep hole drilling process.
- Centric drilling of pistons for stroke measurement systems
- Cilinder pipes
- Internal coolant of cilinder housing or electronics/ press air
- Internal coolant and lubrication system
- Drilling for heattreatment
- Heatsensors and electronics
- Coolant in vacuum chambers
- Weight reduction
- Internal integrated lubrication for bearings etc.
Balancing on the cutting edge of what’s technically feasible, we try to drill all materials from Plastics up to most exotic materials:
- Stainless Steel
Design rules/ tolerances
|4mm - 30mm||Common ELB drilling|
|> 30mm||BTA drilling|
ELB Drilling Depths
|<10||Common twist drills|
|20:1||Special deep hole drilling tools with through-tool high pressure oil|
|100:1||ELB drilling tools on dedicated ELB drilling machine|
|>100||Extreme drilling range, please get in contact with our Design for Manufacturing Engineers for support|
Diameter tolerances/ surface roughness
This high precision operation produces accurate, repeatable holes, with excellent surface finishes. ELB drills hold location to precise tolerances, are sized to exact specifications, produce burr free holes, and can be formed to produce specific shapes in blind holes with minimal machine adaptation.
With the ELB technology in combination with our dedicated deep hole drilling machines we realise H9 tolerances and a surface roughness of Ra 1 -1.6 micron.
With the ELB technology in combination with our dedicated deep hole drilling machines we realise H9 tolerances and a surface roughness of Ra 1.2 -2.0 micron.
Hole Straightness (run out)
- Hole straightness depends on many factors:
- Design of the part
- Hole diameter and dept
- Machining method and cutting parameters
- Material quality and homogeneity
- Drill bush
For ELB and BTA with rotating drill a run-out of 0.8 -1.2 mm/m is the general market standard. For ELB and BTA with rotating workpiece a run out of 0.2-0.4 mm/m is possible. More accurate drilling is possible, please get in contact with one of our deep hole drilling experts.
The straightness is heavily depending on the heat development within a product. This is of upmost importance for holes on the boundary of a part. For this reason drilling should be one of the first manufacturing steps; more materials results in better heat development.
Design for Manufacturing support
You may email us directly at firstname.lastname@example.org for an engineering review or call +31 (0) 523 61 55 51.
You may email us directly at email@example.com for a quote or call +31 (0) 523 61 55 51. To make our quote as accurate as possible, please provide as details/ drawings.
We offer dedicated ‘deep hole drilling’ workshops for engineers. Central topic in these workshops is the design for manufacturing knowledge.