Innovative ToolsAnd Techniques to Implement Flexible Automation

Automation Engineering Inc. (AEi) is a worldwide supplier of automation systems for high precision manufacturing applications, many of which are impossible to implement using manual methods. We also see that a high percentage of our customers' manufacturing applications also require flexible automation to accommodate rapidly changing products with shorter market life cycles for their customers.

Why is Flexible Automation Important?

Unlike tradition fixed or hard automation, flexible automation can manufacture a variety of different products instead of a single product. This wider range of capability has potential advantages in many industries, especially those where product life cycles are short or where product families need to be produced with many permutations. The many different advantages of automation, including lower labor costs, faster cycle times, better process repeatability and higher yields are more easily justified as the cost of implementation spreads over a wider volume of manufactured goods. Flexible automation also supports faster new product introduction and ramp up to production, as long as the level of flexibility is high and effectively implemented.

How to Best Achieve the Benefits

As the level of flexibility in automation equipment increases, the complexity of this equipment also increases. Traditionally, this leads to substantially higher procurement and maintenance costs. It also meant that often the equipment was less available to operate due to maintenance or production changeover time. The best approach to minimizing these drawbacks is to incorporate three primary building blocks to achieve cost-effective flexible automation solutions:

Specific Tools to Facilitate Flexible Automation Implementation

Kinematic couplings typically make swapping out tooling and fixturing modules fast, accurate and repeatable. Using station bases with features such as precision optical breadboards enables quick changes of motion stages, material handling subsystems and processing subsystems for new products or processes. Active air isolation from suppliers such as TMC, Kinetic Systems and Thorlabs minimizes the effect or impact of external vibrations on precision automation systems. This is essential when the positioning accuracies for alignment are in fractions of a micron.

A wide variety of sensing technologies, both contact and non-contact, are used in flexible automation implementation. Software that can be configured to take advantage of these sensing technologies extends both the flexibility and precision of the automation processes. Using a wide range of machine vision and active alignment algorithms that use direct feedback on product and process performance from the activated product itself improves manufacturing yield and cycle time. Monitoring force feedback from grippers is another technique which gives the automation system flexibility in handling, and compensating for, variations in parts.

An integrated machine vision and motion control software platform with integrated machine control sequencing that can be quickly and easily modified is essential for overall station control. It must be designed to monitor and interpret the output of the wide variety of contact and non-contact sensors and instruments used in the feedback process. The control software should also be designed specifically for flexible automation, using process sequencing recipes that can be easily created and modified without traditional programming.

Examples of the Application of Flexible Automation

Fiber Optic Drawing Towers:

Fiber optic drawing towers produce fibers to be used for either illumination, communications, sensing or other applications that transmit light and other electromagnetic waves. The number and type of these applications are growing quickly to support new technologies, making the ability to quickly modify manufacturing process to produce different types and sizes of fiber with different materials important. This requirement makes fiber-optic drawing towers a good candidate for flexible automation, both for R&D and production use.

Companies such as Fiberoptic Systems, Luxtec and National Sign and Signal make bundles of fiber for illumination purposes. They use one type of drawing tower that draws fibers and lays them out on the face of a large 2.5- or 3-m drum in bundles of 10,000 or more fibers. These bundles are later pulled off the drum and cut to lengths as needed to make fiber light guides. The light guides are used for illumination purposes in machine vision, medical devices such as endoscopes and for signage.

To make the exact quantities needed of different sizes and types of fiber bundles during a given shift, PC-based control and associated flexible control software is utilized to minimize work in process and reduce customer delivery time. The control software also provides configurable product recipes so new product types can be quickly and easily introduced into production. An example of this is fiber light guides using smaller diameter fibers which allow for greater packing densities and hence a greater light throughput of a superior product. Making these smaller diameter fibers is also made possible by the protective nose structure for fiber feeding inherent to this draw tower's design. The nose structure shields the drawn fiber from turbulent airflows due to the high speed of the drum so smaller diameter fibers can be drawn without the fibers breaking during the drawing process.

Another type of draw tower is used to draw single optic fibers rather than bundles of fibers simultaneously. To increase flexibility in the type of fibers that can be drawn, the use of a tractor mechanism controlled by adjustable pressure control is the best approach for drawing the fiber. This is in preference to a pinch-wheel that has more commonly been used for drawing single fibers. The combination of the tractor and pressure control minimizes fiber shape distortion, especially for hollow fibers, and accommodates a wide range of fiber sizes and types. Dynamic control of draw speed using laser micrometer measurement of fiber diameter further also adds flexibility to produce different types of fiber accurately and uniformly.

Precision Align, Assembly and Test of Optoelectronic Products:

In some markets for optoelectronics and sensor products, production volumes are too low to justify hard automation. However, it is critical the accuracies and repeatability needed for high product performance and high yields are not sacrificed. Flexible automation stations, used for these applications at companies such as Nortel, BAE Systems, Corning and Covega, must be configurable to make widely different precision optoelectronic products on the same platform using a variety of different processes such as laser welding, adhesive apply and cure and solder reflow. Interchangeable tooling and fixturing designs and subsystems can be used to make this practical and cost effective. Control software that uses force feedback, machine vision and configurable active alignment algorithms is also key.

For production, this has the advantage of being able to produce the right mix of products to meet demand and be able to change this mix quickly over time. A flexible automation station can also be used initially as a development tool to quickly create new products for increased performance, lower cost, new features, etc. The control sequence logic and fixturing can then be transferred quickly to additional machines for production ramp up. Since production is often in another facility (sometimes on the other side of the world), the ability to execute this transfer in minimal time and cost effectively on identical flexible automation platforms is critical. Using the same flexible control software on both the R&D and productions stations with re-configurable process sequence recipes is an important part of implementation.

Camera Module Align, Assembly and Test:

Digital video camera modules are increasingly being included in more and more products including cell phones, automotive and sensing/inspection applications. However, the traditional approach of using single-axis or degree-of-freedom (DOF) alignment of the lens assemblies to the camera sensor during manufacturing doesn't achieve required performance as sensor resolutions increase and customer image quality expectations rise. Product life cycles for these applications are very short given the fast pace of change in the underlying technologies and production ramp-ups need to be very rapid. These requirements call for flexible automation solutions.

Connaught Electronics Limited (CEL) is a European manufacturer for high-end electronics systems that uses flexible camera module manufacturing stations to meet the needs of the premium automotive camera module market. These stations implement a fast 5 DOF automated alignment for attach and test for improved product performance and manufacturing yield. This approach also allows cycle times for align and test to be within a minute or less versus up to 12 or 15 min typical for manual 5 DOF alignment.

These automation stations use configurable active alignment and test algorithms that power up the device as it is being assembled and use the feedback from the device (sensor) itself to guide the assembly. This advanced technique gives the manufacturing stations the flexibility to modify the assembly parameters on-the-fly to optimize the assembly for parts of varying tolerance. A modular pallet design is used for different product packaging and re-configurable target setups are used. A generalized electrical interface supports both digital and analog outputs for a range of different camera sensors (such as from Micron, Omnivision and STMicroelectronics).