Mmanufacturing System

MANUFACTURING SYSTEM вЂ" Assignment

Question 1 :

Lets assume :

Arrival interval ( i.e. time between arrivals = a )

( arrival rate = 1/a )

Machining interval ( i.e. time for one complete machine cycle including load/unload of machine = b )

( machining rate = 1/b )

a & b are constants.

The utilization of the machine is given by b/a. #

A queue can be in one of three states : increasing, decreasing or stationary. What are the conditions necessary for each of these states?

Queues are functional indices which are made use and can be implemented in our job scheduling and work control activities when necessay or needed. For regular users we have basically 3 types of queues.

The increasing queue is for interactive jobs, it is also known as the “now” queue for brief jobs. This type of queue are the basic type of queue’s where it can happen in any situation, where the input is not controlled to meet and adhere to the workstation or manufacturing capability. This queue will never and cannot subside until the loading is stopped or the machine’s cycle time is decreased substantially to meet the process and output requirements by the user.

We also have another queue which is controlled by the hosts for specific uses. It is called the stationary queue. These hosts or servers have their own special queues. The users plan and work their machines or work stations to queue serves of those users who are contibuting to their work. Their jobs have no limits so far as time to execute are concerned. But rather than waste these resources when they are not in use by the patrons queue, regular users are permitted to run jobs on the hosts/workstations via the stationary queue. When leased hosts would otherwise be idle, this stationary queue dispatches jobs to those hosts. These queues are not time limited. But it is preempted by patrons queue jobs, if necessary.

The decreasing queue normally has a limit of days in run time. Users running via this queue are also limited in the number of concurrent job slots. This limit varies by cluster and, in some cases, by host. This is the default queue, the queue that your job will use if you do not specify a queue. It will calculatively determine the number of job queue and also reduce the cycle time and process time substantially to accommodate the number of WIP in the queue. Usually the limit of time calculated can vary from 1 day to 30 days. The total number of concurrent job slots a single user may have is limited as is the total number of jobs slots the queue can fill at one time. Slowly but surely the queue is overcome and solved.

All queues can run both serial and parallel jobs as needed and required.

In this model, what assumptions have been made?

From this model, we can assume that it is using a direct queuing model which can be altered to our own need as to increase / decrease / idle the queue time and effect the machine utilization due to the cycle time being used to predetermine the arrival of the product to machine.

Apart from that, I assume that the formula also can give an assumption of the process requirement that is needed to finish job, whether how soon or how late and how we want to determine the overall cycle time.

Eg : arrival interval of machine part = a = 10 mins

Arrival rate = 1/a = 1/10 = 0.01

Machining interval = b = 10 mins

Machining rate = 1/b = 1/10 = 0.01

Thus the the machine utilization time = b/a

b = 10 mins

a = 10 mins

b/a = 10/10 = 1 #

From this example, it can be an idle queue due to the same demand and process time both by machine and parts arrival. 0 queue.

Hence, by increasing the machine arrival interval, we can have an increasing cycle time, while by increasing the machine time we can have an opposite situation.

What type or types of manufacturing system could this model be applied to?

Manufacturing Systems Types

Let us first look at the essential components of Manufacturing Systems:

The process of designing a manufacturing system therefore must engage upon the design of each of the above four components AND their integration.

Notice that this figure is pretty much consistent with the architecture of Manufacturing systems, which is partially reproduced in the following figure. While the following figure implicitly assumes the important role of the human in each of the modules, I have explicitly placed it separately in the figure above, partly because it helps in highlighting the importance of planning the human aspects of the system.

We first look broadly at these four elements, and subsequently, we shall study each of these aspects in somewhat more detail.

Informal definitions:

Physical Systems refer to all physical aspects of a manufacturing system, including the factories, including the facilities, machines, tools etc., the raw materials, the material handling systems, the work in process, as well as the products.

The Operation refers to all aspects of decision structures that determine how the system functions. For example,