Beginner’s guide to U drill inserts

U drill, one of the most commonly used tools for hole processing, is usually called by different names, such as shallow hole drill, water jet drill, violent drill, fast drill, T-drill, insert drill, etc. The standard name should be indexable insert drill or machine chuck drill. The term “U-drill” originates from the Sandvik Coromant T-MAX U-drill, which was then widely circulated in the industry and gradually evolved into a common name.

What are the types of inserts used in U-drills?

There are several common types of SPMG, SOMT, WCMT, WCMX, the specific data can refer to the following table.

Types WC, SP and SO are the most commonly used U дрель inserts in metalworking. Drilling operations are well suited for the use of indexable insert drills because they reduce the time required for tool changes. The technique of using u drills as roughing is very successful. Deeper cavities or holes can be created by making multiple axial cuts with a drill or milling cutter. This method is particularly suitable for roughing. Since the main cutting forces are concentrated axially along the spindle, it is energy-efficient, effective and reduces the requirements on the machine spindle. Drilling holes for the insert drilling tool is the first step in the internal insert milling process. The unique chipbreaker has a one-of-a-kind design incorporating corrugated edges. This ensures both high edge strength and effective chipbreaking.

Tips for machining with U drill inserts

Irregular surface drilling

Irregular

Convex

Concave

• Use shortest drill possible to minimize vibration tendencies and decrease the effects of deflection
• Recommended start values for cutting speed and lowest recommended feed
• Not recommended for 6–7×DC when concave radius is same or smaller than drill radius

Pre-drilled holes

To keep the cutting force balanced between the central and peripheral insert on an acceptable level, the pre-drilled hole should not be larger than DC/4

Cross hole drilling

Challenges:

• Chip evacuation is affected, might become more problematic
• Deburring in the crossing is hard. Burr formation must be as small as possible
• Causes more tool wear than conventional drilling

Guidelines:

• For holes with different diameter: drill the larger hole first to reduce burr formation
• Start with lowest recommended feed during the crossing of holes
• Not recommended in long-chipping materials due to chip evacuation while crossing holes

Drilling inclined entrances/exits

Generates uneven and excessive forces acting on the cutting edges

• Intermittent cutting as the drill enters/exits the workpiece
• Increases chance of vibration
• Can distort the drilling profile
• Causes more tool wear than conventional drilling

General recommendations:

• Stability is crucial. A small length to diameter ratio will help to keep the tolerances
• Milling a small flat surface is recommended when entering workpieces with a large inclination

Angled or inclined surfaces, entry

• Use shortest drill possible to minimize vibration tendencies and decrease the effects of deflection
• Start with lowest recommended cutting speed and 1/3 of lowest recommended feed (or lower) until fully engaged and then return to normal feed
• 4–5×DC the inclined entry can be angled up to 15º
• 6–7×DC the inclined entry can be angled up to 10º

Angled or inclined surfaces, exit

• Use shortest drill possible to minimize vibration tendencies and decrease the effects of deflection
• Recommended start values for cutting speed and lowest recommended feed (or lower)
• 4–5×DC the inclined exit can be angled up to 15º
• 6–7×DC the inclined exit can be angled up to 5º

Drilling asymmetrically curved surfaces

• Use shortest drill possible to minimize the drill bending outwards from the center, similar to an inclined surface
• Reduce feed to 1/3 of the initial penetration rate for a concave surfaces
• Radius of curved surface should be bigger than drill radius
• Not recommended for 6–7×DC drills

How U drill inserts work and what applications they have

The U drill, also known as a drill with indexable inserts, is a tool primarily used for high-efficiency hole drilling in various materials. Below is a detailed explanation of how a U drill works:

1. Components and Structure

• U Drill Body: This is the main part of the U drill, typically made from a robust material. It has two insert seats: one near the center and one at the periphery. These seats hold the replaceable inserts (cutting edges).
• Inserts: U drills use two indexable inserts: the center insert и peripheral insert. The center insert cuts the material at the core of the hole, while the peripheral insert cuts the outer edges. The outer insert generally does more work as it handles a larger cutting surface.

2. Cutting Process

• Dual Cutting Action: As the U drill rotates at high speeds, both inserts engage the workpiece simultaneously. The center insert cuts the inner part of the hole, and the outer insert cuts the outer diameter. This combination makes the U drill highly efficient because the cutting load is distributed across two inserts.
• Coolant System: U drills are typically designed with internal coolant channels. Coolant flows through these channels and directly cools the cutting zone, reducing heat and friction. It also helps to flush chips out of the drilled hole.

3. Drilling Operation

• Alignment and Positioning: Before drilling, the workpiece is firmly clamped on the machine table or fixture. The U drill’s center is aligned with the intended hole location, either through CNC programming or manual positioning.
• Initiating the Cut: The machine spindle rotates, and the U drill begins to move into the workpiece. The center insert starts the cutting by drilling the core, followed closely by the peripheral insert. As the tool penetrates deeper, both inserts continue to remove material efficiently.
• Chip Evacuation: As material is cut away, chips are generated. These chips are expelled from the hole by the combined action of the rotating inserts and the internal coolant, which helps clear the chips and prevents clogging.
• Completion of Drilling: Once the U drill reaches the programmed depth, the tool retracts, leaving behind a finished hole. Due to the high precision of the inserts and the tool body design, the hole is usually accurate and requires no further reworking.

4. Advantages of U Drills

• Высокая эффективность: Since the U drill uses two inserts to cut simultaneously, it operates at much higher speeds and feeds compared to traditional drills, reducing cycle time.
• Precision: The design of the U drill ensures accurate hole diameters, often eliminating the need for additional finishing operations like boring or reaming.
• Coolant Efficiency: The built-in coolant channels keep the inserts cool during high-speed drilling, reducing wear and extending tool life.

5. Operating Considerations

• Insert Selection: It’s essential to choose the right insert material and geometry based on the workpiece material (e.g., steel, aluminum, cast iron). Using the correct inserts ensures smoother cuts and prolongs tool life.
• Cutting Parameters: The drilling speed and feed rate should be adjusted according to the material and depth of the hole. If the feed rate is too high, it can cause excessive wear or damage to the inserts.
• Coolant Flow: Ensure the coolant system is properly set up and functioning. Insufficient coolant can lead to overheating and premature tool failure.

What Are U Drill Inserts and Why Are They Popular?

U drill inserts are cutting tools used in indexable U drills, specifically designed for high-efficiency hole drilling. These inserts are typically made from carbide or other hard materials, which are capable of withstanding high cutting speeds and temperatures. They are replaceable, meaning once an insert becomes dull, you can swap it out instead of replacing the entire drill, making them cost-effective.

 why U drill inserts are popular:

High Efficiency: U drills with inserts can drill holes much faster than traditional twist drills because they cut using two inserts simultaneously—one for the hole center and one for the perimeter. This reduces machining time significantly.

Cost-Effective: Since the inserts are replaceable, the overall tooling cost is reduced. Instead of replacing an entire drill, you only need to replace the worn inserts.

Versatility: U drill inserts can be used on various materials such as steel, stainless steel, cast iron, and non-ferrous materials. Different insert geometries and coatings are available to suit different applications.

Precision: U drill inserts provide high precision when drilling, often creating holes with minimal need for secondary finishing operations like boring or reaming.

Coolant Delivery: Many U drills are designed with internal coolant channels that cool the inserts during drilling, improving tool life and chip evacuation.

Important Considerations When Using U Drill Inserts

To ensure optimal performance when using U drill inserts, several factors need to be taken into account:

1. Insert Material Selection

Choose the correct insert material (carbide, coated carbide, etc.) based on the workpiece material. Different materials require specific inserts to achieve the best results. For instance, tougher inserts may be needed for drilling through hard steels, while softer materials like aluminum may require a more specialized insert geometry.

2. Cutting Speed and Feed Rate

The cutting speed and feed rate should be appropriate for the workpiece material and insert type. Excessive feed rates can cause insert failure, while too low feed rates may result in poor chip formation or excessive heat buildup.

Consult the manufacturer’s guidelines for recommended speeds and feeds, adjusting based on material hardness and depth of hole.

3. Coolant Management

Ensure that coolant is properly directed to the cutting zone. Coolant helps to reduce heat, prevent tool wear, and aid in chip evacuation. U drills often come with internal coolant channels, but you must ensure these channels are functioning correctly.

Using insufficient coolant or having a blocked coolant passage can lead to overheating, reduced tool life, and poor hole quality.

4. Proper Insert Installation

Make sure the inserts are properly seated and secured in the U drill body. Improper installation can lead to insert shifting, poor hole quality, or even damage to the tool body.

Periodically check for insert wear and replace inserts when they are dull to avoid damaging the workpiece or tool.

5. Chip Evacuation

Monitor chip evacuation during the drilling process. Poor chip removal can cause chips to clog the hole, leading to tool failure, overheating, or workpiece damage.

Adjust feed rates or coolant flow if chips are not being effectively removed from the hole.

6. Hole Depth and Accuracy

U drills are ideal for producing holes quickly, but accuracy can vary depending on the setup and material. For deep holes, ensure proper alignment of the U drill to avoid deviation, which can lead to tapered or out-of-round holes.

7. Insert Wear Monitoring

Keep track of insert wear during use. Worn inserts can negatively affect hole quality and may also cause excess heat, increasing the risk of breakage or damage to the workpiece.

Regular inspections and timely insert changes are essential to maintain hole quality and extend tool life.

By following these guidelines and using the right insert for the application, you can maximize the efficiency, cost-effectiveness, and precision of U drills in your machining operation

Заключение

The U-drill is a drilling tool containing carbide inserts characterized by ease of use and cost-effectiveness. In order to facilitate the machining of a wide range of materials, ONMY U-drill inserts are available in a variety of types and sizes.ONMY U-drill inserts offer an energy-saving and efficient solution, in addition to a high metal removal rate. For high quality U-drill inserts, contact ONMY! Contact us and we will be happy to answer any questions or concerns you may have.