When pricing out a part for a customer, there are several variables to consider, such as power and water consumption, material costs, and direct labor. However, depending upon the stock material and your feed rates, garnet often represents the largest operating cost of waterjet cutting tools. So, it makes sense to optimize this indispensable resource. Fortunately, there are best practices for optimizing garnet use. Let’s explore.
You get what you pay for, especially when it applies to the garnet you use in your waterjet cutting tools. If you skimp on the quality of the garnet you use, you run the risk of inferior or irregular edge finishes and cut interruptions caused by irregular particle sizes clogging the nozzle. On the other hand, choosing the proper garnet size and quality more than compensates for any cost differential.
You have two main types of garnet: hard rock (mined and manufactured) and alluvial (collected and washed). Of these two, the hard rock garnet provides superior results, including:
When you purchase a high-quality garnet abrasive, the mesh size you specify is the size you get due to production practices like crushing, refining, and double-sifting. Poor-quality garnet costs less because it’s less expensive to produce and grade. As a result, your abrasive suffers from poor particle uniformity, directly impacting each cut's quality.
Another best practice involves optimizing the pump pressure and waterflow rate for each part you cut. For best results, you need to consider pump PSI and horsepower. Here’s what to consider:
Another best practice involves adjusting the garnet flow rate before and during the cut. While this practice delivers the most benefits when using hard rock garnet, you can also achieve abrasive savings with alluvial garnet. Optimizing the flow rate involves these steps:
You set a flow rate according to your standard operating procedures before starting a cut. However, the best practice involves watching the cut results and using a Mini Hopper to adjust the flow rate. Incorporating pauses into the cutting program allows you to make flow rate adjustments that minimize abrasive consumption without compromising cut quality.
Best practice requires abrasive calibration tests regularly to ensure peak performance and garnet use optimization. Ideally, you should perform an abrasive calibration weekly or after changing the garnet type and size or modifying equipment. If your project involves costly stock, calibration makes sense before starting the cut. Always follow the OEM recommendations for the calibration process.
Garnet recycling makes economic and environmental sense and ranks high on our best practices list. How does recycling benefit your operation and the environment? The benefits of garnet recycling include the following:
Quality garnet is the best candidate for capture and recycling because of particle size uniformity and sharper edges produced during manufacturing. Regardless of starting quality, cutting grains experience edge wear and fracturing during cutting (garnet fragmentation), and so starting with a harder, sharper, uniform product results in better reclaimed abrasive material.
Best practices in abrasive reuse include the following process steps:
Recharging your recovered abrasive is the “art” aspect of abrasive recycling. Many variables come into play, starting with the material you are cutting. Over time, experimentation with the percentage of recycled abrasive to new will provide the ideal blend for each material type. A 90/10 ratio (recycled/new) might be perfect for soft materials, while you may need a 10/90 ratio for hard and brittle materials.
It never hurts to underscore the importance of planned routine maintenance for all equipment in machining operations. And, given the precision of waterjet components, maintenance is vital to peak performance.
OEMs always provide maintenance recommendations for their products, and that’s the first place to start. Maintenance recommendations fall into a category we call “predictive.” We test our equipment components to determine the Mean Time Between Failure (MTBF). Based on the MTBF, we develop routine maintenance schedules designed to prevent failures in the first place. We also encourage customers to combine visual and predictive maintenance for maximum uptime and output.
Here’s a general summary of the routine maintenance Jet Edge recommends for its waterjets. Keep in mind that each product has specific requirements.
So, how does proper maintenance help with optimizing garnet use? Simple. When your waterjet always operates as designed due to proper maintenance, you significantly reduce the factors that can impact (increase) garnet consumption.
With the economic and environmental benefits of optimizing garnet use, there’s no time like the present to start applying the best practices in this article to your waterjet cutting operations. These proactive steps will reduce spending on new abrasives, improve cut efficiency and edge finish, and reduce waste disposal costs.
Still have questions about garnet use optimization or any of the best practices we’ve covered? Jet Edge engineers will be happy to take your call and share what we’ve learned so you can become a garnet optimization master, too. Fill out our Contact Form, or call the US toll-free: 1-800-JET-EDGE (538-3343). International callers can reach us at +1-763-497-8700.
Since 1984, Jet Edge has been designing and manufacturing Ultra-High-Pressure Water jet technology that doesn't back down. Our systems are used around the world in a broad range of industries from the world's leading airlines, to automotive, aerospace and industrial manufacturers, and machine job shops.
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