MECHANICAL DRILLING
Hole machining is one of the most critical chip removal machining processes and is among the most frequently used operations in mechanical component manufacturing
The technical excellence of Steel Lavorazioni Meccaniche
For over 30 years, Steel Lavorazioni Meccaniche has been recognized for its expertise in mechanical drilling, a critical process in the manufacturing of precision mechanical components.
Thanks to our multi-industry approach and ability to work with a wide range of materials, we meet the demands of complex sectors, including aerospace, food processing, automation, and nuclear industries.
What makes us the ideal partner for companies is our commitment to reliability, precision, and on-time delivery. Additionally, we ensure fully traceable and controlled processes, certified according to the strictest standards of the aerospace and nuclear industries.
WHAT IS MECHANICAL DRILLING?
Drilling is the machining process in which a cutting tool (drill bit) penetrates the workpiece to create a hole.
A hole is considered “deep” when its length exceeds at least 10 times the diameter of the tool, reaching up to 150 times the diameter or more, depending on how the drilling tool is guided within the machine.
Due to the extensive depth range, this process often requires the use of specialized tools and systems, such as gun drills, twist drills, and BTA tools.
This high-precision machining process is widely used for manufacturing thermoforming components, blow molding parts, plastic molds, brass micro-components, medical components, hydraulic parts, mechanical transmissions, and aerospace components. Mechanical drilling plays a crucial role in cooling, weight reduction, and optimizing both thermal and geometric deformation of machined parts.
The best performance in mechanical drilling is achieved by:
Technological parameters such as feed rate, cutting speed, pressure, and flow rate are crucial for chip control in this machining process.
TOOLS USED IN MECHANICAL DRILLING
Various tools and equipment are used to perform mechanical drilling, including: twist drills, gun drills and BTA/STS tools.
Twist drills are typically made from steel, micrograin carbide, HSS, and other materials that offer different cutting tool geometries. They are available with or without internal coolant channels for lubrication and cooling.
These drills are usually used to create a pilot hole by progressively inserting short drill bits, then manually using longer twist drills in multiple steps.
Twist drills generally cover drilling ratios such as 12:1, 20:1 (length-to-diameter), and even 30:1 or more.
The milling machine is the machine tool used for mechanical milling. It consists of:
Gun drills are characterized by a V-shaped flute along the entire length of the drill bit, featuring one or more central holes that deliver high-pressure coolant directly to the cutting edge.
The drill tip has a non-symmetrical shape and rotates around its axis. It is a single-edged tool, non-self-centering, and requires either a pilot hole or a guide bushing. Once positioned, it can self-guide, with force distributed along its peripheral guide pads.
Regrinding the gun drill tip (with a brazed carbide tip) is a necessary operation that depends on wear and the mechanical properties of the material being machined. A gun drill can drill over 1,200 meters during its lifespan due to the numerous possible regrinds.
Coolants used in mechanical drilling include neat oil and emulsified water, specifically designed for deep hole drilling. The coolant flows along the V-shaped flute, carrying away machining chips.
BTA/STS tools consist of a drilling head screwed onto a tube and are exclusively used on deep drilling machines.
A coolant supply unit delivers lubricant to the cutting edges, feeding the circular gap between the hole’s surface and the external surface of the tube on which the drilling head is mounted. Chips and coolant are then expelled through the tube’s inner passage.
This drilling technology is limited to materials with good machinability and a sufficiently large diameter. The wide oil passage ensures excellent lubrication and cooling, while the chip evacuation channel is restricted to the inner tube diameter.
Like gun drills, BTA/STS tools use neat oil or emulsified water coolants for deep hole drilling. In both gun drilling and BTA drilling, the coolant is recovered, filtered, and reused for the same process.
The key difference between BTA/STS tools and gun drills is that the coolant flow rate is higher, but the pressure is significantly lower compared to the gun drilling method.
Various BTA drilling heads are available on the market, including brazed heads, single-insert, and multi-insert versions.
HOW DEEP DRILLING MACHINES WORK
To perform mechanical drilling, specialized drilling machines are used, specifically designed to ensure high-precision machining results.
A fixed head
A fixed head (also known as a chip box) that includes a guide bushing—essentially a targeting system for the drill bit—through which coolant and chips exit the hole before being collected in the underlying conveyor system.
A spindle
A spindle with optimized power and rotational speed for the specific application.
Mobile steady rests
Mobile steady rests (self-adjusting on IMSA machines) to support the gun drill bit or BTA drilling tube.
Drilling machines include a dedicated lubrication and cooling system
Pumps
Pumps for delivering neat oil or emulsified water at the appropriate pressure and flow rates for the application.
tank
A coolant collection tank.
conveyor system
A conveyor system for collecting and separating chips and coolant exiting the drilled holes.
filtration system
A multi-stage filtration system, ensuring effective filtration down to 25 microns.
refrigeration unit
An active refrigeration unit, maintaining optimal temperature control for clean oil.
Depending on the cutting tool used, drilling machines can be classified as:
WHY USE A SPECIALIZED MACHINE FOR MECHANICAL DRILLING?
What is the difference between using a dedicated deep drilling machine and a non-specialized machine tool?
The key difference is that a dedicated drilling machine is specifically designed to optimize the use of gun drills or BTA drills, ensuring maximum efficiency and precision.
Using a gun drill on a non-specialized machine tool, such as a lathe, machining center, or milling machine, requires an additional pilot hole created with a short twist drill.
The process typically involves:
Switching to progressively longer gun drills, if the required hole depth exceeds the overhang tolerance of the shorter drill.
Drilling the pilot hole with a short twist drill.
Using a short gun drill for the initial deep drilling phase.
This method requires manual insertion of each drill bit at different stages, making it a non-automatable and slower process, recommended only for occasional deep drilling operations.
WHY CHOOSE STEEL LAVORAZIONI MECCANICHE FOR MECHANICAL DRILLING?
For over 30 years, Steel Lavorazioni Meccaniche has provided its customers with cutting-edge expertise and advanced technology to manufacture high-precision mechanical components through specialized machining processes.
FULL SERVICE
The company offers a comprehensive service, backed by extensive experience in mechanical drilling and precision machining.
MULTI-SECTORAL APPROACH
Its diverse client portfolio has allowed the company to develop a multi-industry approach, gaining solid expertise in processing a wide variety of materials and building strong capabilities in producing high-performance components.
RELIABILITY AND PRECISION
Steel Lavorazioni Meccaniche serves key industries such as aerospace, food processing, automation, packaging, recycling, and nuclear energy, ensuring:
The company is certified to meet the stringent standards required by the aerospace, military, and nuclear industries, guaranteeing top-tier quality and reliability.
All of this makes Steel Lavorazioni Meccaniche a leading company in the industry and the ideal partner for any industrial business in need of specialized mechanical drilling services