STEP-NC AP-238 is an integrated version of the STEP-NC ISO 14649 standard that enables more data sharing with the other STEP standards for CAD, CAM and CAE applications. This paper describes how STEP-NC AP-238 is being tested for deployment in the United States of America. The tests focused on showing that STEP-NC AP-238 allows multiple CAM systems to send five-axis tool path data to multiple CNC machines without any post-processing. The paper also describes the results of previous work performed on a feature-based implementation of STEP-NC, and explains why US industry has had difficulty in adopting a feature-based implementation as its initial deployment method.
STEP-NC is the result of a ten-year international effort to replace the RS274D (ISO 6983) G and M code standard with a modern associative language. The new standard connects CAD design data to CAM process data so that smart applications can understand both the design requirements for a part and the manufacturing solutions developed to make that part. STEP-NC builds on a previous ten-year effort to develop the STEP standard for CAD to CAD and CAD to CAM data exchange, and uses the modern geometric constructs in that standard to specify device independent tool paths, and CAM independent volume removal features. This paper reviews a series of demonstrations carried out to test and validate the STEP-NC standard. These demonstrations were an international collaboration between industry,
A high-performance liquid chromatographic (HPLC) method is described for the determination of residual levels of cisplatin from extracts of surfaces with very low surface area; from extracts of surfaces of coupons made of Teflon (polytetrafluoroethylene, PTFE), stainless steel, and glass; and in aqueous solution collected after rinsing equipment and parts. Initially, the method was developed to determine cisplatin at concentrations ranging from 20 to 200 ng/ml by direct injection. Retaining the same method conditions, the scope of the method was expanded by the addition of a sample preconcentration step, allowing analyses at levels ranging from 0.5 ng to 20 ng/ml. Preconcentration is necessary for the determination of cisplatin in rinse waters at a quantifiable concentration of about 2 PPB. Under these conditions, the detection limit is about 0.2 to 0.3 ng/ml. Residual cisplatin on different types of surfaces, including surfaces with very low surface area, can be determined by swabbing each test surface with a derivatizing solution. The cisplatin recovered in the swabbing solution can be analyzed by HPLC using direct injection or preconcentration, depending on the expected level of cisplatin in the sample. Initial methods were developed to quantitate at a cisplatin concentration of about 100 PPB or higher in solution extracted from surfaces. However, when surface areas are limited because of the size of the parts, solution concentration becomes very low as a result of the minimum volume required for extraction. To support the application of swabbing techniques to surface analysis, stainless steel, Teflon, and glass surfaces were spiked with cisplatin at 2.5 to 20 ng/cm2. Satisfactory overall recoveries of 90% +/- 10% were obtained from all surfaces. Cisplatin has no ultraviolet/visible (UV/Vis) spectral-active functional group that can be used to detect low levels of cisplatin. Hence, diethyldithiocarbamate (DDTC) was used as a derivatizing agent to increase sensitivity to UV absorption at 340 nm. Diethyldithiocarbamate forms complexes with the platinum in cisplatin to yield a platinum-DDTC (Pt-DDTC) complex with a high molar-extinction coefficient. The Pt(DDTC)2 complex thus formed was chromatographically separated and the quantitated by comparison of its detector response to that of a similarly derivatized standard preparation. DDTC also has application as a cleaning agent for cisplatin (e.g., for production equipment cleaning, spill cleanup). Destruction of cisplatin can be affected by the reaction of cisplatin with this cleaning agent. Derivatization of cisplatin will convert active cisplatin to platinum-DDTC on surfaces or in solution. Final cleaning can be accomplished using a water-for-injection rinse. After such a cleaning process, the rinse water, when collected and analyzed, showed levels of free cisplatin less than the detection concentration of 0.2 PPB and a total platinum concentration less than 10 PPB as Pt-DDTC complex.
STEP-NC is a new data format for manufacturing control. One of its applications is to enable integrated on machine measurement of machining processes using vision systems and other sensors. In this paper we describe the manufacturing process and manufacturing resource models in STEP-NC that can be used to enable this type of measurement. These descriptions include the machine setup so that the configuration of the part can be identified and corrected, the machine kinematics so that the actions of a machine while adding or subtracting material can be verified, and the product tolerances so that the quality of the final part can be predicted and corrected during the machining.
STEP-NC AP-238 is the result of a ten-year effort to replace the RS274D (ISO 6983) M and G code standard with a modern associative language that connects CAD design data to CAM process data. STEP-NC builds on previous work to develop a neutral data standard for CAD data and uses the modern geometric constructs of that standard to define device-independent tool paths, and CAM-independent volume removal features. This paper describes four key factors, or challenges, that had to be addressed to extend STEP-NC AP-238 functionality beyond that offered by other CNC standards. The four factors are difficulties inherent in all CAD/CAM integration projects and can be summarized as follows: the information complexity of geometry, the volume of attributes defined for manufacturing processes, the difficulties of integrating models that span CAD and CAM, and the requirement for easy implementation. We describe an advanced CNC application that uses these four factors and show how STEP-NC AP-238 enhances CNC machining and measurement.
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