Monday, December 22, 2014
Waterjetting 28b - More on abrasive use
The costs of running a high pressure waterjet table divide into two parts, one that covers the basic costs of the system, whether it is running or not, such as building rent, while the second covers those costs that are a part of the actual work. Of the latter costs it is the cost of the abrasive that is often the most significant. This comes about in two ways, since the abrasive must first be purchased for use, and then, after it has been used it must be disposed of. Depending on the materials that were cut, this disposal cost can be significantly higher than the original purchase price. In some work carried out at the High Pressure Waterjet Lab (HPWL) at Missouri University of Science and Technology (MST) in the past we have seen disposal costs that were more than three times the cost of the original abrasive. And one should bear in mind that, as a research lab, the table was used much less than a comparable conventional table in an industrial cutting environment. But we also did not have a cutting operational budget, and so the cost of abrasive was something that we examined, to see if it could be reduced.
The first idea was that we would just recycle the abrasive. The particles of the target materials that were cut are generally much smaller than the abrasive particles themselves, and so it should be relatively easy to remove them from the mix. However, as we looked into the process in more detail, it was clear that it would not be quite as simple as it might, at first, appear. Marian Mazurkiewicz (retired) and Greg Galecki (who now runs the HPWL) carried out studies on the behavior of the particles as they moved through the mixing chamber and were accelerated down onto the target material. They found, as noted in an earlier post, that most of the abrasive was crushed to a smaller size when it passed through the cutting head, and a mix that started out with a particle size of 210 microns as it was fed into the system, was leaving the focusing tube with an average size of 140 microns.
Figure 1. Percentage of abrasive at different sizes after it has passed through a mixing chamber (and before it has hit the target). (After Galecki).
The reason that this is a concern is that, as the particles become smaller, so a point is reached where, depending on the target material, the abrasive no longer has sufficient energy to effectively cut into the target. When cutting into metals such as titanium and steel, our targets of choice in the study, this cut-off grade was at around 100 microns.
Figure 2. Effect of particle size on the cutting performance of an abrasive jet in cutting steel. (The tests were part of a factorial experiment and are thus averages over a number of different test runs at differing abrasive feed rates (AFR and pressures).
Roughly 25% of the mix in the example shown in figure 1 lies below 100 micron at it leaves the chamber. After impacting the target this value increases to more than 50%. Obviously recycling this fine material and re-using it in the cutting process is going to be less effective than removing it from the mix. Generally alluvial garnets will break up more rapidly than mined garnet, because of the structure of the abrasive particles, and thus the percentage that leave the focusing tube at the larger and more effective diameters are lower with the alluvial mix. The results were, we found, confirmed in the cutting results, with alluvial garnet producing a generally shallower depth of cut that would be achieved, other things being equal, in the cutting tests.
A quick word of explanation of the tests we ran, which are described in more detail here. The tests are run at a standard pressure and nozzle size, and at a constant traverse rate, with the depth that the jet cuts into a standard steel at a fixed speed measured over a 4-inch traverse length.
The results of the tests showed that, because of the particle crushing during the cutting process, the abrasive would have to be screened, and for most effective re-use only the larger fraction (on average less than 40%) should be recycled. The rest would be too fine for effective re-use in the operations we were developing. (Although finer abrasive has use in other applications, it would have to be screened and stored). It was interesting to note, and perhaps logical in retrospect, that once the particles had been used once and the larger ones separated out, then the percentage that survived and could be reused a second and third time increased significantly. This is mainly because those particles that had some form of weakness crack (either from weathering or from the mining process) were broken during the first impact, and the particles that survived did not have these cracks, and would therefore inherently be more prone to survive multiple times.
For our purpose, therefore, given that there was a high cost in purchasing the abrasive, and an even higher one in disposing of the contaminated material after cutting (because of the contamination by the target material) there was a potential economic advantage in recycling the abrasive. There were several ways in which the particles can be separated, but a simple screening process, if carried out properly, is quite time consuming, since the particles are required to “sit” on a vibrating screen for several minutes to ensure accurate separation, and this can be labor intensive if it is carried out as a batch process. We tried a number of different ways, including using a counter-flow fluid column that worked well for low feed rates, but the most efficient unit for one operation (we build virtually all of ours, and extensively modified them over time) may not be the best in other cases. (The one that survived the longest was a Wilfey table (though not this one).
In conventional AWJ cutting the abrasive has also to be dried before it can be re-used, and that can also add power and labor costs to the process. Thus, as with many choices that must be made when developing an efficient cutting operation, the best answer is to carry out a series of tests yourself, and run the numbers to decide whether, in the long run, recycling would, or would not, be an effective choice.
The first idea was that we would just recycle the abrasive. The particles of the target materials that were cut are generally much smaller than the abrasive particles themselves, and so it should be relatively easy to remove them from the mix. However, as we looked into the process in more detail, it was clear that it would not be quite as simple as it might, at first, appear. Marian Mazurkiewicz (retired) and Greg Galecki (who now runs the HPWL) carried out studies on the behavior of the particles as they moved through the mixing chamber and were accelerated down onto the target material. They found, as noted in an earlier post, that most of the abrasive was crushed to a smaller size when it passed through the cutting head, and a mix that started out with a particle size of 210 microns as it was fed into the system, was leaving the focusing tube with an average size of 140 microns.
Figure 1. Percentage of abrasive at different sizes after it has passed through a mixing chamber (and before it has hit the target). (After Galecki).
The reason that this is a concern is that, as the particles become smaller, so a point is reached where, depending on the target material, the abrasive no longer has sufficient energy to effectively cut into the target. When cutting into metals such as titanium and steel, our targets of choice in the study, this cut-off grade was at around 100 microns.
Figure 2. Effect of particle size on the cutting performance of an abrasive jet in cutting steel. (The tests were part of a factorial experiment and are thus averages over a number of different test runs at differing abrasive feed rates (AFR and pressures).
Roughly 25% of the mix in the example shown in figure 1 lies below 100 micron at it leaves the chamber. After impacting the target this value increases to more than 50%. Obviously recycling this fine material and re-using it in the cutting process is going to be less effective than removing it from the mix. Generally alluvial garnets will break up more rapidly than mined garnet, because of the structure of the abrasive particles, and thus the percentage that leave the focusing tube at the larger and more effective diameters are lower with the alluvial mix. The results were, we found, confirmed in the cutting results, with alluvial garnet producing a generally shallower depth of cut that would be achieved, other things being equal, in the cutting tests.
A quick word of explanation of the tests we ran, which are described in more detail here. The tests are run at a standard pressure and nozzle size, and at a constant traverse rate, with the depth that the jet cuts into a standard steel at a fixed speed measured over a 4-inch traverse length.
The results of the tests showed that, because of the particle crushing during the cutting process, the abrasive would have to be screened, and for most effective re-use only the larger fraction (on average less than 40%) should be recycled. The rest would be too fine for effective re-use in the operations we were developing. (Although finer abrasive has use in other applications, it would have to be screened and stored). It was interesting to note, and perhaps logical in retrospect, that once the particles had been used once and the larger ones separated out, then the percentage that survived and could be reused a second and third time increased significantly. This is mainly because those particles that had some form of weakness crack (either from weathering or from the mining process) were broken during the first impact, and the particles that survived did not have these cracks, and would therefore inherently be more prone to survive multiple times.
For our purpose, therefore, given that there was a high cost in purchasing the abrasive, and an even higher one in disposing of the contaminated material after cutting (because of the contamination by the target material) there was a potential economic advantage in recycling the abrasive. There were several ways in which the particles can be separated, but a simple screening process, if carried out properly, is quite time consuming, since the particles are required to “sit” on a vibrating screen for several minutes to ensure accurate separation, and this can be labor intensive if it is carried out as a batch process. We tried a number of different ways, including using a counter-flow fluid column that worked well for low feed rates, but the most efficient unit for one operation (we build virtually all of ours, and extensively modified them over time) may not be the best in other cases. (The one that survived the longest was a Wilfey table (though not this one).
In conventional AWJ cutting the abrasive has also to be dried before it can be re-used, and that can also add power and labor costs to the process. Thus, as with many choices that must be made when developing an efficient cutting operation, the best answer is to carry out a series of tests yourself, and run the numbers to decide whether, in the long run, recycling would, or would not, be an effective choice.
Subscribe to:
Post Comments (Atom)
This is a great post. It’s Very informative and well writing.
ReplyDeleteppc advertising
dich vu ke toan thue tron goi dích vu lam bao cao tai chinh tín
ReplyDeletetrung tâm đào tạo kế toán tại tphcm gia
khóa học kế toán thực hành re
công ty dịch vụ kế toán
dich vu ke toan thue tai bac ninh
dịch vụ kế toán trọn gói tại hà nội
dịch vụ kế toán tại tp.hcm
dịch vụ báo cáo thuế
dịch vụ quyết toán thuế uy
trung tâm đào tạo kế toán tại tphcm
trung tâm đào tạo kế toán tại cầu giấy tín
trung tâm đào tạo kế toán tại long biên
trung tâm đào tạo kế toán tại hà đông re
trung tâm kế toán tại thanh xuân
trung tâm kế toán tại bắc ninh
trung tâm kế toán tại bình dương
trung tâm kế toán tại hải phòng
dịch vụ quyết toán thuế tại quận bình thạnh
dịch vụ quyết toán thuế tại quận tân phú
dịch vụ quyết toán thuế tại quận 5
dịch vụ quyết toán thuế tại quận 3
dịch vụ quyết toán thuế tại tphcm
dịch vụ quyết toán thuế tại quận cầu giấy
dịch vụ quyết toán thuế tại quận long biên
dịch vụ quyết toán thuế tại quận hà đông
dịch vụ quyết toán thuế tại quận thanh xuân
dịch vụ dọn dẹp sổ sách kế toán
ReplyDeletedịch vụ dọn dẹp sổ sách kế toán tại thái bình
dịch vụ dọn dẹp sổ sách kế toán tại phú thọ
dịch vụ dọn dẹp sổ sách kế toán tại hưng yên
dịch vụ dọn dẹp sổ sách kế toán tại quận hải dương
dịch vụ dọn dẹp sổ sách kế toán tại hải phòng
dịch vụ dọn dẹp sổ sách kế toán tại quận thanh trì
dịch vụ dọn dẹp sổ sách kế toán tại quận hoàng mai
dịch vụ dọn dẹp sổ sách kế toán tại quận hai bà trưng
dịch vụ dọn dẹp sổ sách kế toán tại quận hoàn kiếm
dịch vụ dọn dẹp sổ sách kế toán tại quận từ liêm
dịch vụ dọn dẹp sổ sách kế toán tại quận ba đình
dịch vụ dọn dẹp sổ sách kế toán tại quận tây hồ
dịch vụ dọn dẹp sổ sách kế toán tại quận đống đa
dịch vụ dọn dẹp sổ sách kế toán tại bắc ninh
dịch vụ dọn dẹp sổ sách kế toán tại quận tphcm
dịch vụ dọn dẹp sổ sách kế toán tại quận cầu giấy
dịch vụ dọn dẹp sổ sách kế toán tại quận long biên
dịch vụ dọn dẹp sổ sách kế toán tại quận hà đông
dịch vụ dọn dẹp sổ sách kế toán tại quận thanh xuân
dịch vụ hoàn thuế gtgt
dịch vụ làm báo cáo tài chính tại huyện củ chi
ReplyDeletedịch vụ làm báo cáo tài chính tại quận bình tân
dịch vụ làm báo cáo tài chính tại quân phú nhuận
dịch vụ làm báo cáo tài chính tại quận gò vấp
dịch vụ làm báo cáo tài chính tại quận thủ đức
dịch vụ làm báo cáo tài chính tại quận bình thạnh
dịch vụ làm báo cáo tài chính tại quận tân phú
dịch vụ làm báo cáo tài chính tại quận 12
dịch vụ làm báo cáo tài chính tại quận 11
dịch vụ làm báo cáo tài chính tại quận 10
dịch vụ làm báo cáo tài chính tại quận 9
dịch vụ làm báo cáo tài chính tại quận 8
dịch vụ làm báo cáo tài chính tại quận 7
dịch vụ làm báo cáo tài chính tại quận 6
dịch vụ làm báo cáo tài chính tại quận 5
dịch vụ làm báo cáo tài chính tại quận 4
dịch vụ làm báo cáo tài chính tại quận 3
dịch vụ làm báo cáo tài chính tại quận 2
dịch vụ làm báo cáo tài chính tại quận 1
dịch vụ báo cáo thuế tại tỉnh bình dương
ReplyDeletedịch vụ báo cáo thuế tại quận bình thạnh
dịch vụ báo cáo thuế tại quận tân phú
dịch vụ báo cáo thuế tại quận 5
dịch vụ báo cáo thuế tại quận 3
dịch vụ báo cáo thuế tại tphcm
dịch vụ báo cáo thuế tại quận long biên
dịch vụ báo cáo thuế tại quận hà đông
dịch vụ báo cáo thuế tại quận thanh xuân
dịch vụ báo cáo thuế tại quận cầu giấy
dịch vụ báo cáo thuế tại gia lâm
dịch vụ báo cáo thuế tại đông anh
dịch vụ báo cáo thuế tại thanh trì
dịch vụ báo cáo thuế tại quận hoàng mai
dịch vụ báo cáo thuế tại quận hai bà trưng
dịch vụ báo cáo thuế tại quận từ liêm
dịch vụ báo cáo thuế tại quận hoàn kiếm
dịch vụ báo cáo thuế tại quận tây hồ
dịch vụ báo cáo thuế tại quận ba đình
dịch vụ báo cáo thuế tại quận đống đa
lớp học kế toán tổng hợp
ReplyDeletelớp học kế toán thực hành
khóa học kế toán tổng hợp tại vinh nghệ an
trung tâm đào tạo kế toán tại vinh nghệ an
khóa học kế toán thực hành
Khóa học kế toán tổng hợp thực hành tại bắc ninh
Khóa học kế toán tổng hợp thực hành tại hải phòng
Khóa học kế toán tổng hợp thực hành tại tphcm
Khóa học kế toán tổng hợp thực hành tại bình dương
Khóa học kế toán tổng hợp thực hành tại hà đông
Khóa học kế toán tổng hợp thực hành tại cầu giấy
Khóa học kế toán tổng hợp thực hành tại long biên
Khóa học kế toán tổng hợp thực hành tại thanh xuân
giá dịch vụ kế toán
Great post. Thanks for sharing...
ReplyDeleteSamsung Washing machine service
Packers and Movers Bangalore - Reliable and Verified Household Shifting Service Providers Give Reasonable ###Packers and Movers Charges. Cheap and Best Office Relocation Compare Quotation for Assurance for Local and Domestic House Shifting and Get estimates today to save upto 20%, ***Read Customer Reviews - @ Packers And Movers Bangalore
ReplyDelete
ReplyDeleteشركة مكافحة حشرات بالمدينة المنورة
شركة كشف تسربات بالمدينة المنورة
شركة تنظيف شقق بالمدينة المنورة
شركة تنظيف موكيت بالمدينة المنورة
شركة تنظيف مجالس بالمدينة المنورة
شركة تنظيف منازل بالمدينة المنورة
شركة تنظيف كنب بالمدينة المنورة
شركة تنظيف فلل بالمدينة المنورة
ReplyDeletehttps://sites.google.com/view/movers-riyadh/movers-mecca
ارخص شركة نقل عفش بالمدينة المنورة
ReplyDeleteشركة نقل عفش بالقصيم
شركة نقل عفش بخميس مشيط
شركة نقل عفش بابها
شركة نقل عفش بتبوك
شركة نقل العفش بالمدينة المنورة
شركات نقل العفش بمكة
شركات نقل العفش
เว็บสล็อตเป็นเว็บเกมส์สล็อตที่เหมาะสำหรับนักลงทุนที่งบน้อยจนไปถึงงบมากฝากถอนไม่มีขั้นต่ำมั่นคงปลอดภัย
ReplyDeleteสล็อตเว็บตรง เป็นเว็บเกมส์สล็อตที่เหมาะสำหรับนักลงทุนที่งบน้อยจนไปถึงงบมากฝากถอนไม่มีขั้นต่ำมั่นคงปลอดภัยสมัครสล็อต ที่นี่ดีที่สุดเป็นเกมส์สล็อตที่ถูกใจสำหรับนักลงทุนที่งบน้อยจนไปถึงงบมากฝากถอนไม่มีขั้นต่ำมั่นคงปลอดภัย
ReplyDeleteสล็อตแตกง่าย ลงทุนน้อยกำไรเยอะฝากถอนไม่มีขั้นต่ำมั่นคงปลอดภัย สล็อตเล่นฟรี สมัครตอนนี้ลุ้นรับเครดิตฟรีทันที
ReplyDelete