Straight Talk on Linear Motion Costs

Straight Talk on Linear Motion Costs

By Danielle Collins, Industry Segment Manager, Bosch Rexroth Linear Motion and Assembly Technologies, Buchanan, Mich.

If you want to learn more, please visit our website linear electric actuators factory.

Reprint Info >>

When evaluating the total cost of ownership (TCO) of linear motion systems, several key factors come into play — from initial research and design to acquisition and startup costs, as well as system operation and maintenance.

Effective Implementation

A precisely implemented multi-axis manufacturing system can significantly reduce production time, boost throughput, and enhance both quality and profits.

In the realm of capital equipment, it's easy to incur unexpected costs if you focus solely on the initial purchase price. An apparently cheaper solution might end up costing more in the long run, especially when it comes to linear motion systems.

Linear motion systems, also known as linear modules or electromechanical actuators, generally integrate a linear drive mechanism — such as a precision ball screw or a toothed belt — with a linear guide system, often a ball rail or cam roller guide assembly, within a housing to create a single linear axis. These systems are available in various sizes and styles, allowing customization into multi-axis systems for different applications. For instance, tiny systems can be configured for laboratory automation, while larger systems can handle heavy automotive components.

More integrated systems often require motors, drive amplifiers, and controllers. Some companies now offer complete, pre-configured Cartesian motion systems to simplify specifications and ordering. Such systems are popular in medical manufacturing and packaging industries, where they eliminate the complexities of mounting and aligning multiple axes, selecting the right motor and drive combination, and designing mounting interfaces, allowing companies to focus on their core expertise.

Belt-drive Linear Actuators

Belt-drive linear actuators usually offer higher speeds and longer lengths compared to screw-drive systems, which typically provide higher precision and load capacities.

TCO Applied to Linear Motion

The TCO principle, first defined in the 1980s to quantify the cost of implementing personal computers at workplaces, has since been applied across various industries, including manufacturing. A well-implemented Cartesian robot or other multi-axis manufacturing system can reduce production time, increase throughput, and enhance quality and profits. However, poor implementation can lead to profit loss due to rework, redesign, or unexpected maintenance costs.

When evaluating the costs of a linear motion system, consider three phases:

• Pre-purchase activities (design and specification)
• Purchasing (ordering, delivery, system assembly, and startup)
• Post-purchase (maintaining and re-purposing the system)

The Pre-purchase Phase

The pre-purchase phase is crucial for implementing a linear motion system. Here, TCO elements depend on the time required to design, specify, and purchase the appropriate system. Good decisions in this phase can save time and ensure smooth startup and operation.

The key to success in this phase lies in properly sizing and selecting the appropriate linear module(s). Many companies offer resources like web-based sizing and selection tools to ease this process. A typical three-axis Cartesian system generally requires around 17 hours of engineering time for accurate sizing. Good sizing tools can reduce this time to less than three hours, and automated drawing generators can offer substantial engineering cost savings.

Cost savings from good planning extend beyond engineering time. A poorly designed system not robust enough to handle the application can lead to waste due to poor performance, lost productivity, and revenue. The extra cost of removing ineffective systems, re-sizing, re-ordering, and re-installing can add up to thousands of dollars, potentially costing machine builders their customers.

The Purchase Phase

Once the linear motion system is chosen and designed, it's time for purchase. Some companies offer a single part number for the complete multi-axis electromechanical system, simplifying the ordering process and reducing the number of vendors, purchase orders, and line items. This can save significant time and money during approval, procurement, and receiving processes. If you need to order a duplicate system, repeat cost savings are already inbuilt.

Time is often spent assembling and starting up the system after its delivery. To minimize costs at this stage, it's crucial to opt for a system that’s easy to install and doesn’t require complex startup procedures. Pre-assembled linear modules and Cartesian systems offer reduced complexity, with around 80% of the assembly, integration, and programming work done by the manufacturer. These cost savings are passed on to end-users by system integration companies using pre-configured Cartesian systems.

Online Sizing Tools

Online sizing tools like Rexroth’s CMS configurator take much of the guesswork out of selecting the right modules for the overall system. Explore them at www.boschrexroth-us.com/tools.

The Post-purchase Phase

Post-purchase maintenance can add significantly to the cost of ownership over a system’s lifetime. Some linear products are advertised as "lubed for life," but it’s essential to understand that this life expectancy often assumes no load. For example, applying a 100-pound load can reduce the component life from 25,000 km to 5,000 km.

To minimize maintenance or replacement costs, select systems with full contact seals to preserve lubrication and prevent contamination. Opt for systems with accessible lube ports or automatic lubrication systems to ease maintenance efforts. Beyond lubrication, some manufacturers offer interchangeable components, allowing easy replacements or upgrades, thus reducing costs and time required for system changes.

Consider more than the quoted price and look at the costs involved in specifying, designing, purchasing, and maintaining the system. Applying TCO considerations can eliminate waste, improve worker satisfaction, enhance revenue and profits, and increase quality.

TCO Tips

• Plan well: size and select the appropriate linear module(s) for your system
• Use web-based sizing tools to reduce engineering time
• Consider pre-assembled linear modules for easy installation and quick startup
• Reduce maintenance with full-contact seals to preserve lubrication
• Save time and money by choosing a system with interchangeable components
• Repair or upgrade parts of the system rather than replacing the whole machine

For more information, please visit ptpa valve exporter.

Pitfalls in Linear Motion System Implementation

• Poorly implemented systems can result in rework, redesign, and unexpected maintenance
• Oversized systems consume unnecessary money and space
• Underperforming systems lead to poor performance and lost revenue opportunities

Bosch Rexroth Linear Motion and Assembly Technologies

www.boschrexroth-us.com

::Design World::

Costs and Capabilities of Pneumatic, Electric Actuators

Costs and Capabilities of Pneumatic, Electric Actuators

Gil Guajardo

The debate between pneumatic and electric actuators is not new. Each type has its own merits, but confusion still exists about which is more suitable for various applications.

For instance, are you considering replacing a compressor and 200 pneumatic cylinders with electric actuators to save on compressor costs? Or are you planning to build a new machine with pneumatics because 30 electric actuators seem too expensive? Making the wrong decision could waste significant amounts of money.

Evaluating and Comparing Competing Technologies

The underlying technologies for pneumatic and electric actuators differ significantly, meaning one cannot replace the other without careful consideration. Both have inherent advantages and disadvantages that must be evaluated regarding performance, component costs, system costs, and productivity gains.

Pneumatic Actuators

Pneumatic actuators offer high force and speed at a low unit cost within a compact footprint, providing more force and speed per unit size than other technologies except hydraulics.

The force and speed of pneumatic actuators can be easily adjusted and are independent of each other. Typically, pneumatic applications use oversized cylinders because they are inexpensive, making it feasible to step up to a larger diameter.

Pneumatics are economical when the compressor capacity matches the scale of deployment. Small compressors are efficient and economical when powering a small number of devices, while large compressors are efficient for larger deployments. Making incorrect calculations can result in unused compressor capacity, which can be costly.

Pneumatic components have low costs, but maintenance and operational expenses can be high. Cylinder replacements, air line installations, and the electricity needed to run compressors add up. According to the Department of Energy, maintenance, equipment, and installation account for about 25% of compressed air costs, with over 75% due to electricity.

The operating cost per pneumatic device must consider compressor load — efficiency decreases with partial load. Turning off compressors when not in use and maintaining systems to prevent leaks can save substantial amounts of electricity.

Analyzing the operating cost per device can be eye-opening, especially if the scale of operations has changed. For example, if 500 devices use a compressor, the cost per device might be $100 annually, but if only 50 devices use the same compressor, the cost per device could rise to $1,000 annually.

Electric Actuators

Electric actuators offer precise control and positioning, suiting flexible processes with low operating costs. They are most economical on a moderate scale where performance advantages are beneficial, and separation of electronics from the actuator is possible.

Common motors used are steppers and servos. Step motors are economical for accurate, lower-speed positioning but may lose sync when under-sized. Servos provide better performance at high speeds but at a higher cost.

Electric actuators' thrust and speed are inversely related, differing from pneumatic actuators. Accurate sizing is critical since increasing thrust or speed necessitates design changes using more expensive components. Proper understanding of application loading ensures optimal performance and minimizes costs.

Component Costs Vs. Operating Costs

Electric actuator components — the mechanical actuator, motor, electronic driver, and motion controller — have high initial costs, but low operating expenses due to the motor's efficient power draw.

For instance, manual production line changeovers can be expensive in lost production and man-hours. Electric actuators can reduce such costs significantly.

When considering replacement costs, operating expenses, and process efficiency, electric actuators' annual costs can be comparable to pneumatics. The scalability and ability to replace individual motion system components separately make electric actuators a viable choice.

The initial cost of actuators should be one of many considerations for cost-efficient automation. Both pneumatic and electric actuators have unique advantages. Accurate upfront assessments ensure that equipment aligns with application requirements, leading to long-term cost savings and efficiency.

Gil Guajardo, This article was originally published in IMPO's September digital edition.

Want more information on linear valve actuator factories? Feel free to contact us.