The tube sheet is typically a round steel plate that has numerous holes drilled into it, which are slightly larger than the outer diameter of the tubes. This design allows for the insertion and securing of the tubes. Tube sheets are mainly used in heat exchangers, boilers, pressure vessels, and various other equipment to hold the tubes in place and seal the medium inside.
The holes in the tube sheet are machined using CNC machines. For this job, we can use a specialized CNC drilling machine for tubesheet, or if we need a bit more power, we can opt for a CNC drilling and milling machine.
In the tube sheet machining process, the quality of the drilled hole wall is really important for how well the product performs and how long it lasts. There are several factors that can affect this finish, but three stand out as the most important: tool wear, chip breaking level, and internal cooling pressure. When we pay attention to these top 3 aspects, we can achieve a better finish for the hole wall, ensuring better overall results!
Tool wear is an important factor that affects the quality of machining finishes. As you spend more time machining, the cutting edge of the tool naturally wears down. This can lead to increased cutting forces and higher temperatures. When the tool is worn, it might cause vibrations and scratches on the machining surface of the workpiece, which can really impact how smooth and polished it looks. Taking care of your tools can help ensure a better finish!
Did you know that when the wear on a tool's back face hits 0.2mm, the surface roughness of the machined part can rise by more than 30%? That's pretty significant! So, it's really important to replace worn tools in a timely manner to keep your machining quality top-notch.
The way chips break during machining plays a big role in how stable the process is and how nice the finished surface looks. Ideally, we want the chips to be small and uniform. This not only helps keep the cutting process smooth but also prevents those pesky chips from getting tangled around the tool and scratching the surface we're working on.
In actual machining, getting chip breaking just right can really make a difference! By tweaking the cutting parameters and choosing the right type of chip breaking groove, you can achieve great results. Long chips can wrap around the tool and create annoying surface scratches, while overly broken chips can wear out your tool faster. Finding that sweet spot is key to ensuring a smooth, high-quality machined surface!
In general, high RPM and high-feed cutting parameters are more likely to produce fine chips. In contrast, low RPM and low-feed settings often result in excessively long chips that wrap around the tool.
The way internal cooling pressure affects the machining finish is really about keeping things cool and ensuring chips are cleared away correctly. When the water pressure is just right, it can help lower cutting temperatures, wear down the tools less, and quickly flush out chips from the machining area.
For the best results when machining tube sheets, it's important to have the right water pressure! Aim for between 10kg/cm2 (142PSI) and 20kg/cm2 (290PSI). If the water pressure is too low, it can struggle to cool the material and remove chips effectively. On the flip side, too much pressure might cause vibrations that negatively impact surface quality. Remember to adjust the water pressure based on the material and machining settings you're using, so you can achieve fantastic results!
These three factors work together and play a big role in determining the finish quality of the hole wall on the tube sheet during processing. In production, it's important to take all these factors into account and find the best combination of tools, cutting parameters, and cooling systems. Doing so will help you achieve the surface quality you're aiming for!
At the same time, with the advancement of processing technology, new tool materials and cooling methods continue to emerge, providing more possibilities for improving processing finish. If you are looking to buy a reliable CNC drilling and milling machine, please reach out to the sales team at EagleTec CNC. We're here to help you find exactly what you need!
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