Ingeniero industrial

Materials Requirements Planning (MRP)
MRP es una herramienta de planeación equipada específicamente para ensamblar operaciones. El objetivo es permitir que cada unidad de producción pueda informar a su proveedor que partes necesitan y cuando se requieren. El proveedor puede ser interno o externo. Junto con MRP II es probablemente una de las herramientas de planeación más usadas del mundo. MRPfue creada para atacar al problema de ‘demanda dependiente’; determinado la cantidad de componentes necesarios conociendo únicamente el numero que productos terminados.
Master Production Schedule (MPS)
El proceso empieza desde la Planeción de Producción. Se debe tener el conocimiento de la demanda, pronóstico y cantidad de producto que debe producirse para almacenar. La etapa de la demandareflejará la disponibilidad de producción de la planta. Dos puntos que se deben considerar en el MPS son el periodo de rendimiento y un horizonte de planeación. El periodo de rendimiento es el tiempo en el que basa la planeación, puede ser diario, semanal o mensual. El horizonte de planeación consiste en determinar que tanto se puede planear por adelantado lo que se determina conociendo la demanday el lead time de cada operación. Existen tres pasos en la preparación del MRP: exploding, netting y offsetting.
Exploding
En esta etapa se utiliza la Lista de Materiales (BOM). La lista muestra cuantos de que componentes se necesitan para cada producto, sub ensamble, ensamble final, producto final…
Netting
El siguiente paso es ‘netting’The next step is 'netting', in which any stock onhand is subtracted from the gross requirement determined through explosion, giving the quantity of each item needed to manufacture the required finished products.
Offsetting
The final step is 'offsetting'. This determines when manufacturing should start so that the finished items are available when required. To do so a 'lead time' has to be assumed for the operation. This is the anticipated timefor manufacturing.
The whole process is repeated for the next level in the BOM and so on until the bottom is reached. These will give the requirements and timings to outside suppliers.
There are three major assumptions made when constructing an MRP schedule:
* The first, and possibly the most important, is that there is sufficient capacity available. For this reason MRP is sometimes calledinfinite capacity scheduling.
* The second is that the lead times are known, or can be estimated, in advance.
* The third is that the date the order is required can be used as the starting date from which to develop the schedule.
Manufacturing Resource Planning (MRP II)This is a development that seeks to address some of the shortcomings of MRP. It includes all of the elements of MRP,it: * is based around the Bill of Materials, * uses a Master Production Schedule (MPS) as its starting point and * uses the three steps of Explosion, Netting and Offsetting to create the initial schedule. However MRP II includes the following four major developments from MRP:1. FeedbackMRP II includes feedback from the shop floor on how the work has progressed, to all levels of the scheduleso that the next run can be updated on a regular basis. For this reason it is sometimes called 'Closed Loop MRP'.2. Resource SchedulingThere is a scheduling capability within the heart of the system that concentrates on the resources, i.e. the plant and equipment required to convert the raw materials into finished goods. For this reason the initials `MRP' now mean Manufacturing ResourcesPlanning. The advantages of this development are that detailed plans can be put to the shop floor and can be reported on by operation, which offers much tighter control over the plant. Moreover loading by resource means that capacity is taken into account. The difficulty is that capacity is only considered after the MRP schedule has been prepared. It may turn out that insufficient time was allowed...