An Error Compensation Strategy for Replication by Rapid Prototyping

1995 ◽  
Vol 117 (3) ◽  
pp. 423-429 ◽  
Author(s):  
M. L. Philpott ◽  
P. A. Green

A generic closed-loop strategy for error compensation is presented which extracts and mathematically models the geometry of sculptured artifacts, and compensates for cumulative error build-up during replication. Experimental results using this strategy demonstrate that a considerable improvement in the accuracy of the end product can be achieved. The replication process involves scanning, CAD solid model creation, rapid prototyping utilizing the stereolithography process, the production of room temperature vulcanized (RTV) molds, the casting of polyurethane parts from the RTV mold, abrasive finishing processes associated with these prototyping processes, and the CNC machining of production molds and dies. At each stage in the replication process, the surface errors (caused primarily by material shrinkage, layer curling, internal stresses, chemical curing phenomena, and material removal during mechanical surface finishing) are tracked and used in subsequent production, through an iterative process of surface fitting and surface compensation.

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Lida Heng ◽  
Yon Jig Kim ◽  
Sang Don Mun

AbstractRecent developments in the engineering industry have created a demand for advanced materials with superior mechanical properties and high-quality surface finishes. Some of the conventional finishing methods such as lapping, grinding, honing, and polishing are now being replaced by non-conventional finishing processes. Magnetic Abrasive Finishing (MAF) is a non-conventional superfinishing process in which magnetic abrasive particles interact with a magnetic field in the finishing zone to remove materials to achieve very high surface finishing and deburring simultaneously. In this review paper, the working principles, processing parameters, and current limitations for the MAF process are examined via reviewing important work in the literature. Additionally, future developments of the MAF process are discussed.


1994 ◽  
Vol 116 (2) ◽  
pp. 144-152 ◽  
Author(s):  
W. R. Dinauer ◽  
N. A. Duffie ◽  
M. L. Philpott

Four algorithms for removing shape and waviness errors in sculptured surface production processes are described in the paper. One of the algorithms employs an open-loop strategy without inspection, error analysis, and error compensation. The other three algorithms employ closed-loop inspection error analysis and error compensation strategies to manipulate control surfaces used in sculptured surface production. Coordinate measurements made on the surface being produced are compared with a designed surface and the results are used to modify related control surfaces that are used to guide processing equipment. Two of the closed-loop algorithms also use intermediate planned surfaces to improve error compensation and production control. Experiments are described in the paper in which the algorithms were tested on an experimental surface finishing system that included an optical probe, grinding spindle, and computer control system integrated with a CNC machining center. The results obtained using open-loop and closed-loop algorithms are compared, and it is shown that surface inspection, surface error analysis, surface compensation, and surface grinding can be iteratively applied to converge rough-machined test surfaces to their designed shape. The closed-loop algorithms are shown to be capable of compensating for disturbances in the finishing process that went undetected when the open-loop algorithm was used. The closed-loop algorithms have significant potential for application in automated finishing systems for molds and dies.


2019 ◽  
Vol 13 (2) ◽  
pp. 174-184 ◽  
Author(s):  
Fang-Jung Shiou ◽  
Assefa Asmare Tsegaw ◽  
◽  

Surfaces of different complex shapes are aspirated part of many scientific measuring devices, medical, astronomical, and other precision activity utilizations. Components at miniaturized level should meet required surface roughness for the intended applications. Surface finishing of freeform and miniaturized components are always difficult and need to look for a new way out. In this study, an attempt was made to improve surfaces roughness of selected, most frequently used, engineering materials using different innovative processes, which can be integrated with CNC machine centers. An advanced automated surface finishing tools such as ball burnishing embedded with load cell, vibration assisted polishing, and self-propelled abrasive multi-jet polishing tools are proposed. Ball burnishing is advantageous for pre-machining process of ball polishing. Using the polishing device embedded with load cell, the constant force polishing is achieved. To reduce the volumetric wear of a polishing ball, vibration assisted polishing device is also integrated. Moreover, self-propelled abrasive multi-jet polishing tool, which achieves 93.33% improvement of surface roughness for lapped optical glass of BK7 has been subjugated from Ra 0.300 μm to 0.020 μm. These tools can be miniaturized and applicable in small micro CNC machining centers.


Author(s):  
Khorssand Haghpassand

Abstract The five-axis constrained and optimal orientation planning is formulated as a design optimization problem that incorporates the process machine’s kinematic constraints with the workpiece and tool geometry, to obtain a constrained setup orientation which exploits the maximum capabilities of existing machines. This work will introduce this problem, and will obtain the setup orientation for two different types of rotation structures, i.e., tool rotation and table rotation in O(N) time. Further, the obtained constrained setup orientation, will be augmented to incorporate the workpiece surface magnitude, along with different machine rotation structures, to obtain an optimal setup orientation for different machine rotation structures. The drilling process is also introduced and formulated as additional constraints to the optimization problem. The primary application of the introduced algorithms, is the machining process, where, they can efficiently reduce the number of tool motions and surface finishing processes. However, the solution is very suitable for many manufacturing applications, such as inspection, assembly, robotics, painting, welding, aerospace, electronic surface mount technology, and etc.


Author(s):  
Shadab Ahmad ◽  
Ranganath M Singari ◽  
R S Mishra

Magnetic abrasive finishing (MAF) is one of the finishing processes which produces nano finished surfaces. The material removal process is in the form of microchips. The present paper introduces a novel work based on the principle of MAF for flat surfaces. The experiments were conducted on titanium material to investigate the response of MAF on hardness. Matlab has been used to evaluate the performance. The results obtained from the experimental investigations revealed that the hardness improves with MAF. The surface morphology of finished surface was studied with the help of SEM images


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