• International Journal of Precision Engineering and Manufacturing
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• 제5권3호
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• pp.62-68
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• 2004

Effectiveness of a corrective machining algorithm, which can construct the proper machining information to improve motion errors utilizing measured motion errors, is verified experimentally in this paper, Corrective machining process is practically applied to single and double side hydrostatic bearing tables. Lapping process is applied as a machining method. The machining information is obtained from the measured motion errors by applying the algorithm, without any information on the rail profile. In the case of the single-side table, after 3 times of corrective remachining, linear and angular motion errors are improved up to 0.13 $\mu\textrm{m}$ and 1.40 arcsec from initial error of 1.04 $\mu\textrm{m}$ and 22.71 arcsec, respectively. In the case of the double-side table, linear and angular motion error are improved up to 0.07 /$\mu\textrm{m}$ and 1.42 arcsec from the initial error of 0.32 $\mu\textrm{m}$ and 4.14 arcsec. The practical machining process is performed by an unskilled person after he received a preliminary training in machining. Experimental results show that the corrective machining algorithm is very effective and easy to use to improve the accuracy of hydrostatic tables.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.44-48
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• 1996

This paper describes the effects of thermal deformation in electromagnetic chuck on the grinding accuracy. Gringing process is the last machining process and decisive in saving past other machining cost. The thermal deformation of grinding machine is unavoidable and affect seriously ginding accuracy. The thermaldeformation of electromagnetic chuck is one of important thermal problems. Heat generation of magnetic chuck is analyzed and measured. The temperature disturibution in chuck is elliptical form with high temperature in center of chuck. The thermal deformation form of chuck is changed with time to mountain form. The grinding experiment shows that the thermal deformation of magnetic chuck influence strongly machining accuracy as much as the headstock

• 한국기계가공학회지
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• 제11권2호
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• pp.152-158
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• 2012

A newly developed attachment type high-speed spindle can be easily attached to the conventional CNC machining center to allow high-speed machining with low investment costs. This study has focused on the application of a conventional CNC machining center equipped with an attachment type high-speed spindle. A specimen of plastic mold material has been machined to compare the cutting effectiveness of the high-speed machining center and the conventional machining center with the attachment type high-speed spindle respectively. The rotational accuracy of the spindles are measured by a transmission optic measurement system and the surface roughness of the workpiece in accordance with revolution speed(rpm) of the spindle are investigated respectively. As the experimental results, it was shown that the surface roughness of the machined workpiece was $3.42{\mu}mR_{max}$, $0.46{\mu}mR_a$ in the case of attachment type spindle and $1.81{\mu}mR_{max}$, $0.275{\mu}mR_a$ in the case of the high-speed machining center. Moreover, the mean rotational accuracy was $7.57{\mu}m$ in the case of the attachment type spindle and $7.39{\mu}m$ in the case of the high-speed machining center.

• 한국정밀공학회지
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• 제22권9호
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• pp.188-193
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• 2005

To provide the various machining materials with excellent quality and dimensional accuracy, high -speed machining is very useful tool as one of the most effective rapid manufacturing processes. However, high-speed machining is not suitable for microscale thin-walled structures because of the lack of the structure stiffness to resist the cutting force. A new method which is able to make a very thin-walled structure rapidly will be proposed in this paper. This method is composed two processes, high-speed machining and filling process. Strong workholding force comes out of the solidification of filling materials. Low-melting point metal alloys are used in order to minimize the thermal effect during phase change and to hold arbitrary shape thin-walled structures quickly during high-speed machining. To verify the usefulness of this method, we will show some applications, for examples thin -wall cylinders and hemispherical shells, and compare the experimental results to analyze the dimensional accuracy of typical parts of the structures.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.739-742
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• 2000

Micro machining technology has been studied to fabricate small size and high accuracy milli-structure products. To perfectly overcome the conventional mechanical machining methods, the chemical mechanical micro machining(C3M) process was developed. The mechanism of C3M process is that chemical solution etches the material and results in the generation of the chemical reacted layer, and the mechanical micro tool subsequently removes the layer. From the fundamental experiments, the C3M process has been founded to have the advantages of lower machining resistance, tool wear, and higher surface quality and form accuracy than conventional methods. This study focuses on the micro grooving of both the metallic material(SKDII, A1) and hard brittle silicon oxide.

• International Journal of Precision Engineering and Manufacturing
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• 제7권3호
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• pp.47-50
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• 2006

High-speed machining is a very useful tool and one of the most effective rapid manufacturing processes. This study sought to produce various high-speed machining materials with excellent quality and dimensional accuracy. However, high-speed machining is not suitable for microscale thin-walled structures because the structure stiffness lacks the ability to resist the cutting force. This paper proposes a new method that is able to rapidly produce very thin-walled structures. This method consists of high-speed machining followed by filling. A strong work-holding force results from the solidification of the filling materials. Low-melting point metal alloys are used to minimize the thermal effects during phase changes and to hold the arbitrarily shaped thin-walled structures quickly during the high-speed machining. We demonstrate some applications, such as thin-walled cylinders and hemispherical shells, to verify the usefulness of this method and compare the analyzed dimensional accuracy of typical parts of the structures.

• 한국정밀공학회지
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• 제24권6호
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• pp.45-50
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• 2007

The aspheric lens has become the most popular optical component used in various optical devices such as digital cameras, pick-up lenses, printers, copiers etc. Using aspheric lenses not only miniaturizes and reduces the weight of products, but also lower prices and higher field angles can be realized. Additionally, plastic lenses are being changed to glass lenses more recently because of low accuracy, low acid-resistance and low thermal-resistance in the plastic lenses. Currently, one fabrication method of glass lenses is using a glass-mold method with a high precision mold core for mass production. In this paper, DOE (Design Of Experiments) and compensation machining were adopted to improve the surface roughness and the form accuracy of the mold core. The DOE has been done in order to discover the optimal grinding conditions which minimize the surface roughness with factors such as work spindle revolution, turbine spindle revolution, federate and cutting depth. And the compensation machining is used to generate high form accuracy of the mold core. From various experiments and analyses, we could obtain the best surface roughness 5 nm in Ra, form accuracy $0.167\;{\mu}m$ in PV.

• 한국CDE학회논문집
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• 제4권3호
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• pp.247-258
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• 1999

With the contemporary CAD/CAM system, where the tool path is generated and verified purely based on the geometric operation, geometric accuracy of the machined surface cannot be guaranteed dut to the cutting mechanics, meaning that the cutting mechanics should be incorporated in some fashion. In this paper, we incorporate the instantaneous cutting force and the tool deflection phenomena in predicting the machined surface for the finish-cut and milling operation. For the given NC dat including cutting conditions, the developed algorithm computes cutting force and deflection amount along the tool trajectory, and outputs the 3D graphic model of the machined surface together with error analysis. The validity and accuracy of the presented method has been tested by the actual cutting experiments. Experimental results and accuracy enhancement method together with implementing architecture of the VMCS (Virtual Machining CAM System) are discussed in the paper.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.895-898
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• 1997

These days, most of new materials, which is in use widely as cutting process materials have a characteristic in common. That is hard cutting. So, it happens that hardness by cutting temperature. And hardness on cutting process has an effect on tool wear or life shortness of tools. To solve these problems hot-machining is proposed. When a material is heated, organization of material is soften. So cutting process becomes easy. When such a hot-machining method applies on drilling process and then heated material is processed, cutting force is less than usual drilling process cutting force. In this paper, when a material is heated, cutting force on drilling process is measured. It is decided that the best suitable temperature area. And it suggest that the better hot-machining condition as surface accuracy is measured.

• 한국기계가공학회지
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• 제13권3호
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• pp.89-95
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• 2014

The increasing level of demand for multi-tasking machines requires a saddle with an ultra-precise machining accuracy level of $15{\mu}m$, as such a saddle is one of the main components of these machines. The manner of achieving ultra-precise machining accuracy mainly depends on the fixed forces. In this paper, we optimized the number of contact points and the contact positions to reduce the deformation of the saddle while it is machined. The performance levels of the proposed optimal jig and fixture are determined by measuring the flatness, parallelism and perpendicularity of a machined saddle. The machining accuracy is found to be lower than $15{\mu}m$ at all measured points.