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Circular Pocket Milling Service
Are you looking to make round holes in metal or plastic? Circular pocket milling is a special way to cut clean, round pockets in your parts. Let’s learn how it works in simple words!
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20+ Years
Istar Machining's years in the industry
300,000 square feet
The size of Istar Machining's factory
856 CNC machines
Our CNC equipment count
2000+ skilled workers
Istar's number of skilled machinists/operators
What is Circular Pocket Milling?
Circular pocket milling is when a machine uses a spinning cutting tool to make round holes in materials. Unlike regular drilling, this method can make wide, flat-bottomed holes with very smooth walls.
At Istar Machining, we use this method to create perfect round pockets in many materials like:
- Aluminum parts for airplanes
- Steel molds for car parts
- Plastic cases for medical devices
- Metal parts for machines
Why Choose Circular Pocket Milling?
Circular pocket milling gives you many benefits over other cutting methods:
- Super Smooth Finish: Gets walls smooth without extra work
- Very Exact Size: Holes are the right size within 0.001 inches
- Flat Bottoms: Unlike drilling, the bottom is perfectly flat
- Works on Many Materials: Cuts aluminum, steel, plastic, and more
- Tools Last Longer: Special cutting paths make tools work better
How Circular Pocket Milling Works
When we do CNC pocket milling for round holes, our machines follow these steps:
- The machine starts with a tool in the middle of where the pocket will be
- It moves in special paths (like a spiral) to slowly remove material
- The tool cuts in trochoidal motion(fancy word for a special curved path)
- For deep pockets, the tool goes down in steps to avoid breaking
Important Tools and Settings
Here’s a helpful table showing tools and settings we use for different jobs:
Tool Size | Best For | Speed (RPM) | Material | Special Notes |
6-25 mm | Airplane parts | 8,000-24,000 | Titanium | Ball end mills for smooth corners |
10-20 mm | Car molds | 12,000-18,000 | Steel | Special coated tools last longer |
8-15 mm | Medical parts | 15,000-22,000 | Plastic | 30% stepover for smooth finish |
12-32 mm | Valve bodies | 10,000-16,000 | Stainless steel | Tools with coatings work twice as long |
6-12 mm | Electronics boxes | 20,000-24,000 | Aluminum | Feed rate: 0.2 mm per tooth |
Materials and Their Best Uses
Different materials are better for different jobs. Here’s what works best:
Metals
Aluminum
Stainless Steel
Mild Steel
Brass
Titanium
Aluminum
Aluminum (Common Grades: 6061, 7075, 5052, 2024) is lightweight, corrosion-resistant, has excellent thermal and electrical conductivity, and is very machinable.
Good for:
- Housings and enclosures
- Jigs, fixtures, and tooling
- Automotive and aerospace components
- Heat sinks and thermal management parts
- Manifolds and fluid handling blocks
- High-speed prototypes
Why customers love it: “It provides an outstanding balance of strength, weight, machinability, and cost-effectiveness, making it versatile for countless prototyping and production applications.”
Stainless Steel
Stainless Steel (Common Grades: 303, 304, 316, 17-4 PH) offers excellent strength, high corrosion resistance, temperature resistance, and a hygienic surface finish.
Good for:
- Medical devices and surgical instruments
- Food processing equipment
- Marine hardware
- Chemical processing components
- Architectural fittings
- Components requiring high durability and wear resistance
Why customers love it: “Its superior corrosion resistance and strength ensure parts last even in harsh environments, ideal for demanding applications.”
Mild Steel
Mild Steel (e.g., 1018, A36) is a cost-effective ferrous metal known for its good machinability, weldability, and strength. It is ferromagnetic.
Good for:
- Structural components and frames
- General-purpose fixtures and brackets
- Machine parts not exposed to corrosive environments
- Prototyping where high strength isn’t critical
- Weldments requiring pockets
Why customers love it: “It’s an affordable and easy-to-work-with material for general engineering purposes where corrosion resistance isn’t a primary concern.”
Brass
Brass (e.g., C360) is an alloy of copper and zinc known for its excellent machinability, good corrosion resistance, electrical conductivity, and aesthetic appearance.
Good for:
- Plumbing fittings and valves
- Electrical connectors and terminals
- Musical instruments components
- Decorative hardware
- Bushings and bearings (low friction)
Why customers love it: “It’s one of the easiest metals to machine, allowing for fast production of intricate parts with good mechanical and electrical properties.”
Titanium
Titanium (e.g., Grade 2, Grade 5/Ti-6Al-4V) is known for its high strength-to-weight ratio, excellent corrosion resistance (especially against saltwater and chemicals), and biocompatibility. Machining requires specific approaches due to its properties.
Good for:
- Aerospace structural components
- Medical implants and surgical devices
- High-performance automotive parts
- Marine applications
- Chemical processing equipment requiring inertness
Why customers love it: “Offers incredible strength and corrosion resistance at a low weight, perfect for high-performance and biocompatible applications where other metals fall short.”
Plastics
PEEK
Delrin (Acetal)
Nylon
Polycarbonate
Acrylic (PMMA)
PEEK
PEEK (Polyether Ether Ketone) is a high-performance engineering thermoplastic with exceptional mechanical strength, high-temperature resistance, chemical inertness, and wear resistance.
Good for:
- Aerospace components
- Medical implants and devices (biocompatible grades)
- Semiconductor handling parts
- Bearings, seals, and wear components
- Applications involving high temperatures or harsh chemicals
Why customers love it: “It maintains its strength and properties under extreme conditions – high heat, aggressive chemicals, and high mechanical stress.”
Delrin (Acetal)
Delrin (Acetal / POM) (Polyoxymethylene) is an engineering thermoplastic known for its high stiffness, low friction, excellent dimensional stability, and good wear resistance.
Good for:
- Gears, bearings, and bushings
- High-precision mechanical parts
- Electrical insulators
- Fixtures and jigs
- Parts requiring low moisture absorption
Why customers love it: “It machines beautifully to tight tolerances and offers great mechanical properties, low friction, and stability at a reasonable cost.”
Nylon
Nylon (PA, Common Grades: 6, 6/6) is a versatile engineering thermoplastic known for its toughness, good wear resistance, and decent chemical resistance. It can absorb moisture, affecting dimensional stability.
Good for:
- Wear pads and guides
- Rollers and wheels
- Gears and sprockets (where high precision isn’t paramount)
- Structural components requiring toughness
- Insulators
Why customers love it: “It’s a tough, abrasion-resistant, and cost-effective plastic suitable for many mechanical applications, especially involving friction or impact.”
Polycarbonate
Polycarbonate (PC) is a strong, impact-resistant, and transparent thermoplastic. It maintains rigidity over a wide temperature range.
Good for:
- Machine guards and safety shields
- Optical components (lenses, light pipes – requires polishing after milling)
- Clear manifolds and housings
- Prototypes requiring toughness and transparency
- Electrical insulators
Why customers love it: “It provides exceptional impact strength and transparency, making it ideal for protective components and applications where visibility is key.”
Acrylic (PMMA)
Acrylic (PMMA / Polymethyl Methacrylate) is known for its excellent optical clarity, weather resistance, and rigidity. It’s more brittle than Polycarbonate but easier to polish to a high shine.
Good for:
- Display cases and signage
- Light guides and optical lenses (requires polishing)
- Transparent housings and covers
- Architectural models
- Fluidic viewing windows
Why customers love it: “Offers glass-like clarity and is easy to machine and polish, perfect for aesthetic applications and display purposes.”
CNC Products Produced by Istar Machining
Common Uses for Circular Pocket Milling
People use circular pockets in many different parts:
How We Make Sure Quality is Perfect
When we make circular pockets, we check them carefully:
- Measure Size: Every pocket is checked with digital tools
- Check Smoothness: We test how smooth the walls are
- Look for Problems: Special cameras look for tiny problems
- Test Fit: We make sure parts fit together perfectly
Advanced Techniques We Use
For the best results, our experts use these special methods:
- Spiral toolpathsthat move smoothly without stopping
- Trochoidal millingfor removing material without heat
- Special CAM softwarethat plans the perfect cutting path
- High-feed millsthat can remove material very fast
- Circle-segment end millsfor very smooth wall finish
Why Choose Istar Machining?
When you need perfect circular pockets, our 5-axis machining center can help:
25% Faster
Our special methods cut time by 25%
Expert Team
Our workers know how to make perfect pockets
Top Machines
We use the best CNC machines from Germany and Japan
Quality Control
Every part is checked three times
Fair Prices
Get high quality without high cost
Ready to Start Your Project?
If you need circular pockets in your parts, we’re ready to help! Our team can make your design come true with perfect round cavities in any material.
Get a free quote today! Just send us your drawings or 3D models, and we’ll show you how our CNC milling can make your parts perfect.
Frequently Asked Question
A: We can make pockets up to 10 times deeper than they are wide, depending on material.
A: We can make pockets as small as 1mm in diameter with special micro-tools.
A: We use special holders, slower speeds, and high-pressure coolant to stop vibration.
A: For aluminum, we use 0.1-0.3 mm per tooth with special coated tools.
A: Yes! Our machines can make walls at any angle from 0-90 degrees.
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