Ramazan Rıdvan SEKMEN, 030080083, 9th week words# part2

2-Boolean Operation (Group: Design)

A Boolean operation usually affects two objects at any one time, and is the basis of the binary systems that underline most of computing. Boolean opertations are absolutely fundamental in CAD, and allow the creation of complex forms and compositions by their succesive application to objects that may initially be quite simple. Several of the later case studies illustrate just how important they are in generating form. Learning how to think in terms of applying successive Boolean operations to generate a particular form is essential for CAD users. Examples of some Boolean operations; add, subtract,intersect.

(P. Szalapaj, CAD principles for architectural design: analytical approaches to computational representation of architectural forms, p. 75)

New and better explanation

The map overlay algorithm is a powerful instrument that can be used for various other applications. One particular useful one is performing the Boolean operations union, intersection, and difference on two polygons PI and P2. See Figure 2.7 for an example. Note that the output of the operations might no longer he a polygon. It can consist of a number of polygonal regions, some with holes.

     

       To perform the Boolean operation we regard the polygons as planar maps whose bounded faces are labeled PI and P2, respectively. We compute the overlay of these maps, and we extract the faces in the overlay whose labels correspond to the particular Boolean operation we want to perform. If we want to compute the intersection P1∩P2, we extract the faces in the overlay that are labeled with PI and P2. If we want to compute the union P1U P2, we extract the faces in the overlay that are labeled with P1 or P2. And if we want to compute the difference P1\P2,  we extract the faces in the overlay that are labeled with P1 and not with P2.

       Because every intersection point of an edge of P1 and an edge of  P2 is a vertex of  P1∩ P2,  the running time of the algorithm is O(nlogn + klog n), where it is the total number of vertices in P1 and P2, and k is the complexity of P1∩ P2. The same holds for the other Boolean operations: every intersection of two edges is a vertex of the final result, no matter which operation we want to perform. We immediately get the following result.

Corollary 2.7  Let Pi be a polygon with n1 vertices and P2 a polygon with n2 vertices, and let it n:=n1 + n2. Then P1 ∩ P2, P1 U P2, and P1 \ P2can each be computed in O(nlogn +  klog n) time, where k is the complexity of the output.

( De Berg, M. , Cheong, O., Van Kreveld, M. (2008).Boolean Operations. Computational Geometry: Algorithms and Applications (pp. 39,40). )

3-Boring Cycle (in G-coding) ( Group: Programming)

The boring operation requires that the tool move at a programmed feedrate when it is between points R and Z.The format of the statement for calling the boring cycle subroutine is G85XxYyZzRrFfLl

(Chang C.H., Melkonof M.A.,NC Machine Programming and Software Design Practice Hall,p.48)

New and better explanation

G81 It is a canned cycle for drilling holes in a single drill stroke without pecking. Its motion                                              is feed down (into the hole) and rapid up (out of the hole). A Z-depth must be included.

G82  It is a canned cycle for counter boring or countersinking holes. Its action is similar to G81, except that it has a timed dwell at the bottom ol the Z-stroke. A Z-depth must be included.

G85 It is a canned cycle far boring holes with a single-point boring tool. Its action is similar to G81, except that it feeds in and feeds out. A Z-depth must be included.

G86 It is also a canned cycle for boring holes with a single-point boring tool. Its action is similar to G81, except that it stops and waits at the bottom of the Z-stroke. Then the cutter rapids out when the operator depresses the START button. It is used to permit the operator to back off the boring tool so it does not score the bore upon withdrawal. A Z-depth must be included.

G89 It  is another canned cycle for boring holes with a single-point boring tool. Its action is similar to G82, except that it feeds out rather than rapids out. It is designed for boring to a shoulder. A Z-depth must be included.

( Zhang, P. (). Table 7.4. Advanced Industrial Control Technology (p.288). )

4-Muri ( Group: Management)

Overburdening People or Equipment - This is in some respect on the opposite end of the spectrum from muda. Muri is pushing a machine or person beyond natural limits. Overburdening people results in safety and quality problems. Overburdening equipment causes breakdowns and defects. ( Jeffrey K. Liker, The Toyota Way, McGraw-Hill, 2004, p.114 )

New and better explanation

Muri is all the unreasonable work that management imposes on workers and machines because of poor organization, such as carrying heavy weights, moving things around, dangerous tasks, even working significantly faster than usual. It is pushing a person or a machine beyond its natural limits. This may simply be asking a greater level of performance from a process than it can handle without taking shortcuts and informally modifying decision criteria. Unreasonable work is almost always a cause of multiple variations.

To link these three concepts is simple in TPS and thus Lean. Firstly, muri focuses on the preparation and planning of the process, or what work can be avoided proactively by design. Next, mura then focuses on how the work design is implemented and the elimination of fluctuation at the scheduling or operations level, such as quality and volume. Muda is then discovered after the process is in place and is dealt with reactively. It is seen through variation in output. It is the role of management to examine the muda, in the processes and eliminate the deeper causes by considering the connections to the muri and mura of the system. The muda and mura inconsistencies must be fed back to the muri, or planning, stage for the next project.

 ( Hounshell, A.D. (1984). Types of wastes. From the American System to Mass Production, 1800-1932: The Development of Manufacturing Technology in the United States (p. 399). )

5-International tolerance grade (IT) ( Group: IT)

A group of tolerances that vary depending on the basic size but that provide the same relative level of accuracy within a given grade.

(Edward G. Hoffman Christopher J: Mccauley,Shop reference for students and apprentices,p:223)

New and better explanation

International tolerance (IT) grade is a system of tabularized tolerances found in the ANSI standards and the Machinery 's Handbook that vary based on the basic size. There are eighteen grades ranging from IT01, ITO, IT I ... to...IT 16. The Iower the IT number, the tighter the tolerance. The IT grades in Figure GNT 8 ranging from 01 to about 8 are used for measuring instruments, 8 to 16 for materials, 5 to 11 for defining fits, and 12 to 16 for large tolerances.

( Sexton, T.J. (). General Tolerance. A Concise Introduction to Engineering Graphics and Supplemental Workbook (p. 84). )