Planning in production systems Slovak University of Technology Faculty of Material Science and Technology in Trnava

Resource and capacity planning Resource planning is a set of forward planning tools to help people balance future demand and supply, to predict capacity problems with enough time to do something about them, to create a load leveled master schedule, and to project supplier requirements well in advance. Manufacturing planning and control entails the acquisition and allocation of limited resources to production activities so as to satisfy customer demand over a specified time horizon.

Production planning, at its core, production planning represents the beating heart of any manufacturing process. Its purpose is to minimize production time and costs, efficiently organize the use of resources and maximize efficiency in the workplace. The identification of the relevant costs is also an important issue. A planning problem exists because there are limited production resources that cannot be stored from period to period.

Capacity planning Capacity planning is the process of determining the production capacity needed by an organization to meet changing demands for its products. In the context of capacity planning, "capacity" is the maximum amount of work that an organization is capable of completing in a given period of time.

A discrepancy between the capacity of an organization and the demands of its customers results in inefficiency, either in under-utilized resources or unfulfilled customers. The goal of capacity planning is to minimize this discrepancy. Demand for an organization's capacity varies based on changes in production output, such as increasing or decreasing the production quantity of an existing product, or producing new products. Better utilization of existing capacity can be accomplished through improvements in Overall Equipment Effectiveness.

Capacity can be increased through introducing new techniques, equipment and materials, increasing the number of workers or machines, increasing the number of shifts, or acquiring additional production facilities. Capacity is calculated: (number of machines or workers) x (number of shifts) x (utilization) x (efficiency). Utilization of the production facilities -> 70-80%  Desirable increase of capacity utilization  The less utilization – the more expensive production  The better capacity utilization – the better productivity

Production lines  First is known the product, time structure and after that are the machines obtained.  It is not allowed to occur the idle capacity -> the are used single-purpose machines Minor types of manufacturing  there are machines, and after that is recognized, which products is the company able to produce

Methods of planning the utilization capacity Forward planning:  Forward plan is a document that results from the process of forward planning. In broad terms it sets out the aims and objectives of your organization over a defined period, matched against resources and staff responsibilities.  A forward plan can be as long or as short as necessary, depending on the scale of your organization and what is appropriate to you, but it should always include an associated action plan.

Backward assembly planning An assembly planning system that operates based on a recursive decomposition of assembly into sub assemblies, and analyzes assembly cost in terms of stability, directionality, and manipulability to guide the generation of preferred assembly plans. The planning in this system incorporates the special processes, such as cleaning, testing, labeling, etc. that must occur during the assembly, and handles non reversible as well as reversible assembly tasks through backward assembly planning.

Capacity and time restrictions Causes conflicts, which have to be solved -> there exists 2 possibilities:  it is necessary to take into deliberate the real capacities (capacity restrictions) and then is build the schedule – it is used by forward planning  Capacities are quasi infinite and there are used terms required by the user. In case of the conflict possibility, i its necessary to solve this problem (supplementary capacities or modification of the Schedule) - it is used by backward planning

Operative plan capacity balancing Aim of the capacity balancing  Possibilities verification of planned production tasts by hardware device and by workers  Measure adoption for production tasks harmonization with possibilities of production Capacity balancing steps  setting the production capacity  setting the capacity for planned production tasks realization  comparison of disposable and necessary production capacity and receiving arrangement for disproportion removing

Setting the production capacity Capacity  Capacity planning is the process of determining the production capacity needed by an organization to meet changing demands for its products.  Capacity of the production unit may be determined by many ways and express in natural, time and value units of measure

The most objective and most exact expression of the production capacity is in natural units  Amount of definite products, which certain production facility or a group of production facilities is able to produce in certain period  use – for capacity balancing only in conditions of higher types manufacturing (production in large series, mass production with small range of goods

production capacity expression in time units  maximum possible time usage of the machinery, workers or production plane in some period  expression by the time fund – calendar, nominal and effective time fund  calendar time fund conjunction of calendar days in a year (365 days) and hours in a day (24h) is the base of capacity production of continual production  Nominal time fund conjunction of workdays and hours in working shift (in machine industry usually 2 shifts = 16 hours)  Effective time fund determined on the base of nominal time fund, by subtractions of the time needed for repairs and machinery adjusting

Setting the capacity necessity for operative plan tasks assurance The second step the operative plans of the capacity balancing is the calculation of the capacitive load with plan tasks. Self capacity balancing Disposable capacity comparison to capacity consumption ® usually is determined the existence of capacitive disproportion

Capacity and resources planning After setting the time of production preparation, times needed for individual operation, date of start and production finish -> capacity plan verification – if there are available capacities - the goal is to assure observance of terms and cut-down the idle time Costs planning target – total costs definition for job realization and its minimalization

Production capacity of the machines and production facilities calculation Qp = Tp * Vp Qp- production capacity couched in natural units Tp- usable time fund in hours Vp- power in natural units per 1 hour The production capacity calculation through the capacity of work difficulty – used in machine manufacturing by mechanical working

t k = t k 1 * k 2 t k - capacity of the work difficulty in hours t- standard of the work difficulty in nh (normohours) k 1 - standard fulfilling index k 2 - progression index Q p = T p t k Calculation of the production capacity: k c = Q s Q p k c - total production capacity utilization coefficient Q s - real production volume Q p - production capacity

Factors that affect the level of production capacity utilization  production plan  real working time  machinery performance utilization Capacitive reserve – production volume, which can be able to be produced by full production capacity utilization  divergence Qp - Qs total production capacity utilization coefficient  synthetic indicator  real reached volume of production Qs

if is the production capacity calculated by formula Q p = T p t k i.e. through the usage of capacitive standard of work expenditure, it is possible to measure it as follows: Q s Q p T s T p t k t s = t s - real work expenditure of the product