Details

Written by Katie Allen

Parent Category: Big Blue Saw Blog

Created: 27 March 2019

The evolution of a produced part from start to finish requires brain power and labor, first from the part designer and then to those who take the design and make it a reality. Big Blue Saw is a place where real people make the difference in producing great parts with the best technology possible.

One of the main assets in the Big Blue Saw shop is the TECHNI waterjet, TJ3000, which produces parts out of many different materials that include, for example, aluminum, steel, plastic and wood. The waterjet uses a water stream mixed with an abrasive garnet at high velocity and pressure, to make parts for robots, electronics, scientific equipment and much more. It can make a few parts or several thousand parts per production run, as well as both simple and complex part geometries. Its main benefit is that it uses material efficiently by nesting the parts tightly and can cut with no special fixtures or tool changes. The efficiency provided by the waterjet can often translate to quicker production time and lower cost for the customer.

Behind the waterjet, however, includes manpower in the shop. Two of those people at Big Blue Saw include Clint Sikes, shop manager and waterjet technician, and Simon Arthur, the company’s founder and president.

1. Ensuring appropriate designs

Parts start on the computer as a CAD (computer-aided design) file, which is a 3-D model or a 2-D drawing. The waterjet can cut in 2-D, or a flat pattern saved as a .DXF file. The design can be saved in millimeters or inches, so it’s important to confirm the unit type with the shop manager. In addition to checking the unit type, the shop manager has to ensure no scaling is applied, and the file is saved as a 1:1 ratio. Otherwise, something intended to be 1 ft. could come out as 1 in.

Sikes says the biggest issue he experiences in the production process is incomplete files. While the drawing might appear complete to the customer, the waterjet software will find any and every flaw in a drawing.

“The most common (flaw) is unconnected or crossed lines at intersections and hard angles,” Sikes says. “This will create a ‘lead in’ or ‘lead out’ in the incorrect places. What I mean by that is the software will start its cut on a part surface instead of what we call the drop or unused material. We just ask that customers take the time to really inspect their files or drawings for any flaws before sending it to us.”

Above all, customers should be sure to do their research ahead of time to achieve success in their waterjet-produced part.

“Whether it’s a work project, an art piece or jewelry, take a good hard look into everything that goes along with it,” Sikes says. “This includes material – its weld-ability, its weight and the finish of different metals. Make sure your drawing or print conforms to the capability of a waterjet in order to get realistic expectations on your finished product.”

Have more questions on how to make the process of making parts, start to finish, much smoother? Arthur says customers can find several more tips in the Big Blue Saw’s guide to designing on the waterjet.

2. Getting the design to the waterjet

Once the part design is approved for cutting, the .DXF is imported into the waterjet software. From there, compensation is applied. The shop manager has to tell the software the size of the nozzle, which determines the diameter of the water stream (typically .040 in.). Without adjusting for outside or inside compensation (offsetting the stream inside or outside of the part’s appropriate dimensions) the part would not be cut correctly. It takes human skill to check the diameter and adjust on occasion, as parts wear out. Adjustments are crucial to ensuring the parts are correct in size.

In the software, the shop manager must enter the material size on the waterjet table, such as a 4 ft. x 8 ft. piece of steel. Then the waterjet will nest parts within that piece of material. Say a customer has 100 different parts to cut out of that piece of steel (25 of Part A, 40 of Part B, 15 of Part C and 20 of Part D). The software helps determine where to nest these while wasting as little of the material as possible (also called maximizing sheet utilization), but the shop manager can manually adjust the nesting as well. The key here is to maximize the number of parts cut out while leaving about 0.125 in. between each part.

Arthur says it’s important to note the company can do small and large quantities of parts! The top 5 percent of the Big Blue Saw customers amount to about 50 percent of the business, and individual orders less than $500 are about one-third of total sales. The Big Blue Saw team is willing and able to work prototype designs as well as production runs.

Thickness and type of material (steel vs. aluminum) is also important to enter into the software. Harder materials such as steel cut slower than softer materials such as aluminum. Also, the thicker the material, the slower the waterjet cuts. Big Blue Saw stocks a lot of common material, but the company also orders material for special parts.

Edge qualities are important to note in the software. Customers should let the shop manager know if they prefer a coarse vs. fine edge to the part. Obviously, the finer edge will take longer to cut, and the more time the waterjet spends on the part, the more expensive the part will be. The shop manager can preview the cut path on the waterjet screen before cutting the part, see the order of cutting and estimated cutting time, which helps with developing quotes for various projects.

3. Prepping the machine

Manpower is needed to check the waterjet over, ensure the water is turned on and confirm abrasive is in the abrasive hopper. The abrasive garnet is a really fine sand material that assists with cutting.

“Garnet is essentially sand paper grit minus the paper,” Sikes says. “It all starts with making sure our garnet hopper is full and ready to run. Garnet comes in 55 lb. bags that get dumped into the hopper, which can hold about 2,000 lbs.”

When the waterjet is cutting, water goes into a pump to pressurize to 55,000 PSI, and then the abrasive mixes with water stream before it comes out of the nozzle. The abrasive intensifies the water to cut through the materials. The abrasive removal system (ARS) with the waterjet helps circulate water out of the tank through filters and strain the abrasive out to keep the machine clean and operational.

“The garnet ends up in the bottom of our tank,” Sikes explains. “The removal of our garnet from the base of the tank is handled with our ARS. With help from a pumping system, garnet and water are pumped into a separate tank where the abrasive is allowed to settle and the water is returned to the waterjet tank. Considering we run through close to 3,500 lbs. of garnet a week means this is a constant but necessary process.” 

In addition to making sure the hopper is full of garnet, manpower is also needed to load the material onto the waterjet table before cutting can begin.

4. Completing the parts

After the waterjet does its magic in cutting the parts, the shop manager must pick up those parts out of the machine and may have additional post-processing based on the customers’ needs. This could include grinding, deburring, tapping threads, etc. for that specific part. Then the parts will be on their way to the customer!

5. Maintaining the waterjet

The shop manager must perform machine maintenance so that it is calibrated appropriately and parts will be within tolerance. Abrasive flowing through the machine and nozzle causes wear and tear and erodes away edge of nozzle. Components in cutting head become worn out and need replaced. The stream can cut through slats in table that holds the material, and these need to be replaced on occasion as well.

Sikes says those consumables – nozzles, orifices and high-pressure valves – are replaced most frequently. Determining when these consumables need to be replaced means monitoring proper water pressure and part tolerances. The most time-consuming component of waterjet maintenance, however, is working with the garnet.

Machines such as the waterjet are important for creating parts, and while we are all thankful for these technologies, it still takes a team of people to get the job done!