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IST Precision develops a wide range of industrial automation and high-end precision instrumentation devices. This article explores the critical role of flexure rotational pivots in achieving exceptional motion control within these instruments. IST in general uses these precision pivots in ultra precision applications including laser steering gimbals and surface profilometer sensors for the inspection industry.

Introducing C-Flex: A Vendor in Precision Flexure Bearings

C-Flex [] plays a vital role in our success. They are a valued vendor who supplies us with high-quality flexure bearings. These bearings enable frictionless and exceptionally precise motion in meticulously designed mechanical devices.

The Need for Frictionless Motion

In precision instrumentation, achieving smooth motion at the nanometer or sub-arc second level is paramount. Traditional bearings can introduce friction, leading to non-linear motion and errors in the nanometer range. This ultimately compromises instrument performance.

Several options exist for rotary-motion bearings, including air bearings, jeweled bearings, and ceramic bearings. While air bearings excel in achieving near-zero friction and smooth motion, they can be expensive to operate, requiring dry air and additional design space.

Flexure Bearings: A Compact and Cost-Effective Alternative

For applications with limited space (e.g., satellites) and small angular range requirements, flexure bearings offer an attractive alternative. They boast several advantages:

  • Zero friction: Ensures smooth and highly linear motion.
  • Compactness: Saves valuable space within the instrument.
  • No air requirement: Eliminates the complexity and cost associated with dry air systems.

However, it’s important to note that flexure bearings typically have a small amount of rotational stiffness and a limited angular range which need to be accounted for in the design.

IST Precision: Experts in Flexure Design

While C-Flex doesn’t disclose the specific spring steel material and heat treatment used in their bearings, we understand the importance of exceptionally high yield stresses for flexure pivots. In critical applications, these pivots must maintain precise rotation angles over millions of cycles. In other flexure designs that IST designs we tend to use, materials like 17-4 SS with an H900 heat treatment, known for exceeding 1000 MPa yield stress. This enables the flexure mechanism to reach higher stresses leading to increased bearing life and capability to reach millions of rotational cycles.

Cost-Effective and Versatile

Flexure pivots are a cost-effective solution in a precision application, typically ranging from $50-$100 per pivot in low quantities. Pivot size is a key cost factor, with our designs often utilizing some of the smallest commercially available bearings (1/8 mm or 3.175 mm OD barrel size).

C-Flex: User-Friendly Features

The C-Flex website provides valuable resources for instrumentation designers, including information on bearing loads and clamping methods. We particularly appreciate their laser engraving of part numbers on the outer diameter of the pivots. This simple yet effective feature helps prevent mix-ups during assembly, especially when using multiple pivots with varying torsional rigidity.

Pivot Design Options

C-Flex offers two main pivot body types:

  • Single End Bearing: One end is clamped to the device’s frame, while the other end flexes and rotates.
  • Double End Bearing: Both ends are clamped to the frame, with the middle section free to flex and rotate.

The choice depends entirely on the specific application and instrument design. IST has experience utilizing both types of bearings in various projects.

Clamping Methods for Flexure Pivots

Here are three common clamping methods for flexure pivots:

  • Squeeze Clamp: A traditional method that mechanically clamps around the pivot. While effective, it requires more space and often screws, which might not be ideal for all compact designs.
  • Set Screws: An alternative method but carries the risk of pivot slippage. If using screws, opt for soft-tipped ones.
  • Bonding:Offers the most compact approach and is ideal for designs requiring minimal parts. However, it also carries the highest risk since the bearings are permanent and can’t be removed during a prototype development phase of a project.

Featured Design: A Case Study in Precision for Surface Profilometer Sensors

The CAD model below showcases an interesting design utilizing a flexure bearing. This design features a small shaft (1.2 mm diameter) with a custom diamond tip bonded to its end. The shaft is part of a rotating mechanism that employs a flexure bearing pivot within the green body.

Using custom displacement sensors (differential capacitance sensors), we can detect motions of the shaft relative to the green body down to single digit nanometers. While the sensor itself is crucial, the flexure bearing enables frictionless and highly accurate movement of the shaft about the pivot’s rotational axis.

Furthermore, precision motion stages (not shown) allow our surface profilometer tip to scan along a surface. By monitoring the sensors with a very fast sampling rate (exceeding 10,000 samples per second), we can acquire detailed surface profile data. Ultimately, this design with the flexure pivot allows us to create a simple and elegant contact based profilometer sensor.

IST Precision

For over 20 years, IST has been a leader in precision engineering and automation. We specialize in tackling complex challenges, including intricate robotic EOAT tooling, nanoscale motion systems, advanced laser processes, and high-precision pick-and-place solutions for microscopic parts.

IST Precision

However, IST is expanding its offerings to encompass larger-scale automation and manufacturing process development. To accommodate this growth, we recently acquired the entire building, bringing our total space to 20,000 square feet. This expansion empowers several key strategic initiatives:

  • Increased Capacity and Parallel Projects: Our larger automation machine design and controls teams can now handle more projects simultaneously. This eliminates the phased approach necessitated by our previous space constraints. We can now manage large-scale material handling projects through design, fabrication, and factory acceptance testing concurrently. Additionally, our new, modern, and air-conditioned warehouse optimizes assembly operations, especially during North Carolina’s hot summers.
  • Enhanced In-House Capabilities: Our expanded shop services allow us to bring more capabilities in-house.  In particular, our new welding and fabrication area enables us to create large-scale weldments in-house, ensuring adherence to our strict quality standards, and project deadlines. The shop also features several multi-axis CNC machines for rapid prototyping of parts for both internal development and customer production runs.
  • Streamlined Electrical Integration: Our expanded assembly warehouse now houses a dedicated electrical machine panel shop. Our certified electricians can handle build-to-print projects for electrical cabinets, keeping panel builds in-house to maintain project schedules.
  • Advanced Prototyping and Testing: The expansion includes state-of-the-art electronics, optics laboratories, and additive manufacturing capabilities. This is crucial for IST’s growing precision engineering team, allowing for quick turnaround prototyping and testing before full-scale automation machine design. This focus on cutting-edge technologies sets IST apart in the southeastern US.

Call to Action:

If you’re in the area, we invite you to contact us for a tour of our new facility!

Automation and Engineering Needs

IST’s team is working with cutting-edge robotics on two exciting automation work cells currently in development. These projects showcase our ability to deliver solutions for a wide range of applications.

Micro-Scale Part Pick and Place with Fanuc Scara:

Our first work cell tackles the intricate task of rapidly picking and placing microscale parts with precise control. To achieve this, we’ve integrated a Fanuc SR-3ia Scara robot with a camera, optimized lighting, and an Asyril vibratory feeder. This combination allows our vision system to identify correctly oriented parts within the feeder and pick them up rapidly, regardless of initial rotation. The Fanuc SR-3ia was selected for its compact size, throughput speeds, field reliability, and excellent service. Over the next month our team will complete build, programming, and integration of this system.  The image below shows the robot on a simple test stand to enable our programmers to setup code prior to the entire automation work cell (not shown) being built. We look forward to meeting and exceeding our customers needs in the months to come.

Large-Scale Automation with Kuka Robots:

While we excel at small part material handling, IST also has a team of experts with extensive experience in designing and building large-scale material handling systems. Our second work cell underway features two powerful Kuka KR 140 R3200-2PA industrial robots. This will be used to handle a heavy end of arm tooling as well as the need for large reach and access in an automation line.  Our process will be able to handle a wide variety of parts with over 100 product variations being presented to this robotic work cell.

To ensure accurate picking of these diverse products, we’re integrating custom multi-zoned vacuum grippers with the robots. Additionally, Cognex vision cameras will be employed to further enhance the picking process. It’s important to note that IST’s dedication to thorough analysis was a key factor in winning this project. Through extensive robotic simulations conducted collaboratively with Kuka’s team, we were able to demonstrate the need and benefits of two robots to achieve optimal cycle times, ultimately surpassing our competitors. Safety remains paramount, and we’re currently installing guarding and completing custom robotic welded pedestals to securely fasten these powerful robots to our factory floor.

These projects highlight IST’s robotics and imaging capabilities. Our team is adept at tackling challenges across the spectrum, from small-scale precision handling to large-scale automation. We look forward to partnering with you to develop innovative solutions that meet your specific needs. Stay tuned for more to come on these projects.