Every manufacturer aims to get the best-cut quality when using industrial cutting processes. A better cut quality enhances the visual appeal of the part. At the same time, it eliminates the need for secondary finishing processes.
Evaluating the water jet cutting-edge quality can be a useful parameter to provide comparative results. Manufacturers can know how this technology fares against other cutting processes. Additionally, it can help in achieving better production results.
This article will have an in-depth discussion on the edge quality in waterjet cutting. You will also learn the different techniques to achieve high-quality cutting results.
How is Water Jet Cut Quality Defined?
Water jet cut quality is different grades that define how well the process cuts the workpiece. Manufacturers can know if their part will have nice square corners, rough edges, or a taper cut. A high cutting-edge quality corresponds to a smoother finish of the part. Additionally, it also means producing accurate parts.
What is the Accuracy of a Waterjet Cutting Machine?
The accuracy of a waterjet cut is the measure of the deviation of the cut from its intended position. A lesser deviation means a more accurate cut and a better edge quality.
The deviation is measured as ‘tolerance’. The aim of achieving better cut-edge quality is to lower tolerance as much as possible.
It is practically impossible to have zero tolerance in any machining process. However, waterjet cutting brings this value extremely close to zero. This is why waterjet cutting has one of the most accurate edge qualities among all machining processes.
What are the Different Water Jet Edge Qualities?
Water jet edge quality is divided into five different classes. These classes are graded from 1 to 5, 5 being the highest quality that can be achieved. Here is a detailed explanation of each of these qualities with details such as the use cases and cutting speed:
Edge Quality Grade 1: Separation Cut (Q1)
Separation cut quality (Q1) applies when a fast production of parts is required. It produces parts with a rougher edge quality. It is common for edges to have striations. However, it has faster cutting speeds.
Specifications of Separation Cut
- Cutting Speed: Very Fast
- Edge Quality: Poor
- Striations: Highly Present
Edge Quality Grade 2; Through Cut (Q2)
Through Cut aims for faster production while limiting the striations on edge. While Q1 is roughly cut, Q2 goes easy on the roughness. Through cut is also considered of inferior quality in relation to higher-grade cuts.
Specifications of Through Cut
- Cutting Speed: Fast
- Edge Quality: Poor
- Striations: Present
Edge Quality Grade 3: Clean Cut (Q3)
A clean cut is also known as a standard cut. Most common standards for edge quality require these types of cuts. They have sufficiently fast speed with few striations. The stations are generally present on the lower layers of the cut thickness.
Specifications of Clean Cut
- Cutting Speed: Moderate
- Edge Quality: Acceptable
- Striations: Present on the lower layers of the cut
Edge Quality Grade 4: Good Edge Finish (Q4)
A good edge finish is often considered high-cut quality. The striations are negligible and barely visible. However, it requires cutting at slower speeds.
Specifications of Good Edge Finish
- Cutting Speed: Slow
- Edge Quality: Good
- Striations: Negligble and barely visible
Edge Quality Grade 5: Excellent Edge Finish (Q5)
Excellent edge finish is the best in terms of cut quality. Q5 cuts by Techni Waterjet machines are visibly and physically better than the best quality cuts of other cutting methods. This is an exceptional edge quality with no striations.
Specifications of Excellent Edge Finish
- Cutting Speed: Slowest
- Edge Quality: Best
- Striations: None
Can You Mix and Match Different Edge Qualities?
Yes, it is very easy to mix different waterjet edge qualities. This is usually done by adjusting the cutting speed of the waterjet machines. Matching different edge qualities is useful when cuttin internal and external areas of a part simultaneously. The internal areas that are not visible can have lower edge quality. The external, prominent areas can have Q4 or Q5 edges.
What are the Factors Affecting Waterjet Edge Qualities?
Waterjet edge qualities can depend on multiple factors. Factors affecting precision are usually the ones that affect the cut quality..
Here are the different factors that you should consider for the best cut quality:
- Cutting Speed: Cutting speed is one of the most important parameters in edge-quality waterjet. Lower cutting speeds will bring out a better edge quality. An important thing to note is that very low cutting speeds can have an increased kerf angle.
- Abrasive Mixing Tube Length: Most waterjet cutting involves the addition of abrasive to the waterjet stream in a mixing chamber. This mixing chamber should be long to produce a uniform abrasive mixing. Shorter mixing tubes can reduce edge quality in abrasive waterjet cutting.
- Waterjet Stream Diameter: Small waterjet stream diameter produces higher-quality cuts. However, a small stream diameter also operates at a reduced cutting speed. Therefore, the waterjet stream diameter and the nozzle size affect the waterjet cutting edge quality.
- Nozzle Height: Nozzle height can be crucial for edge quality. Too much nozzle height creates a rounding effect on the top edge of the cut. Additionally, the kerf angle also increases. Lower heights work best for the best quality waterjet cutting.
How Does Workpiece Material Affect Cut Quality?
The workpiece material can play an important role in the cut quality. In this regard, material machinability influences the edge quality.
Materials with poor machinability can have striations or rough edges even with Q5 cuts. These require further careful precautions based on the type of material.
On the other hand, materials with good machinability can provide exceptional edge quality even on Q3 and Q4 speed settings.
How Does the Edge Quality Differ For Thin, Thick, or Stacked Parts?
The material thickness influences edge quality significantly.
Thin parts have the best edge quality even at higher cutting speeds. This is because there are lesser chances of layered striations in thin workpiece materials.
Thicker materials have a greater scope of striations. Therefore, the best results in edge quality come when speed decreases.
The same goes for multiple stacked workpieces as well. In case of stacked workpieces, the lower layers can have slightly reduced cut quality as compared to the upper layers.
How Do Software Features Help Ensure a High-Quality Cut?
CAM software can be important to achieve similar results with high quality. CAM software process the changes in geometries. This change is coupled with the change in feed rate and other parameters.
Quality CAM software will make these transitions optimally, thereby providing good results. Poor software can cause bad quality in transitions like corners, lines to curves, and curves to lines.
Can 5-axis Cutting Affect Cut Quality?
Multi-axis machining, like the 5-axis setups, has the cutting head at a close distance to the workpiece. This leads to a reduction in vibrations and higher-quality waterjet cutting.
Additionally, 5-axis machining also increases the speed at which manufacturing is done. Therefore, manufacturers prefer 5-axis waterjet cutting when speed and quality are a concern.
Does Abrasive Usage Affect Cut Quality?
Yes, the use of an abrasive can influence the cut quality in waterjet cutting. Abrasive waterjet cutting provides better quality results when working on harder materials.
However, pure waterjet provides better quality results for soft materials like rubber and paper due to a lower kerf width.
Which Waterjet Edge Quality To Choose For Your Next Project?
Q5 edge quality turns out to be the best for any project. However, Q5 can have a considerably slow speed. This can be a deal breaker for manufacturers looking for mass-volume production.
Additionally, higher cutting-quality waterjet grades mean a higher cost of production.
Therefore, most manufacturers go with Q5 as the most economical and yet acceptable quality grade.
Tips to Optimize Waterjet Cut Quality
There are some tips you can follow to improve the cut quality of the waterjet cutting process:
Using the Right Software:
The right software can be the difference between a smooth and rougher edge quality. Therefore, investing in good nesting software is important. Techni Waterjet provides high-quality nesting software with all its machines. This means that you don’t have to go through the trouble of finding the right CAM software for your requirement.
Improper calibration often leads to unwanted defects in the waterjet cut parts. Even minute deviations in areas like the cutting head distance can lead to pronounced changes in the outcome. Therefore, doing a proper calibration before using the machine is vital.
Choice of Garnet
There are many options when it comes to the garnet abrasive. Uniform garnet with a fine size provides the best quality results. However, it also increases the cost of the abrasive for the process. Therefore, find the right balance between garnet quality and the price of waterjet cutting.
Many operators make the mistake of thinking that higher water pressure is important when cutting harder materials. That is not correct. Every material comes with a recommended water pressure for optimal results. Choose the values prescribed by the manufacturer in this regard.
Waterjet machines are heavy industrial equipment that requires regular maintenance. Follow the maintenance cycle as prescribed by the manufacturer. Some parts like nozzles and seals require replacement after certain intervals.
Before starting working on the actual project, cut a test part from the same material. This will show you how the final part will turn out. Based on the test part, you can make any changes to the machine settings as required.
Water jet cutting is the favorite choice of professionals due to the high-quality results that this technology provides.
You can get even more highly accurate edge quality by following the tips provided above.
Techni Waterjet is one of the world leaders in manufacturing high-quality waterjet cutting machines & systems for various applications and industries.
Our waterjet cutters can achieve all five grades of cutting-edge quality. Feel free to contact us and get professional advice from our experts.