Norm time in the technological process - MorekTECHTechniki Wytwarzania i Procesy Technologiczne

norma czasów technologicznych - wyróżniający obróbek

Norm time in the technological process 3.33/5 (3)

— 22 February 2016

The standard of technological times (norm time) – determined at the end of the traditionally developed technological process. The general definition defines the standard of machining time as the amount of time necessary to carry out specific activities in given organizational and technical conditions, by a defined number of employees. Providing for [4] the norm of technological times may include all activities carried out by man, technological machine and means of transport. An exception is conceptual (creative) work, for which you can effectively use only a specific schedule with the final date (dead line). The biggest challenge for standardizing working time are technological processes of high time consumption, unique or made to order (eg unit production, repair services).

The standard of technological times is calculated in order to:

production planning,
determining the costs of remunerating employees,
determining the cost of the product.

Calculations of the technological time standard are performed primarily for individual technological operations. It should be assumed that the same activities in different enterprises, with different organizational and technical conditions, take a different amount of time.

Fig. 1 shows the standard of machining times.

Fig.1 Diagram of the technological times norm.

The following base conditions were adopted:

the correct choice of machine tool and technological tooling was made,
the workpiece meets the requirements (overall dimensions, material),
correctly selected machining allowances,
employees have appropriate qualifications,
work organization is at the right level,
the service of the technological station is correct.

The norm of time in equations

The time norm can be determined by the equation:

where: t – technology norm time, t_pz – preparatory and final time, t_j – the unit time.

Preparation and completion time (preparatory and final time) – time of activities related to preparation for completion and completion of a given technological operation. When machining a part series, this time occurs only once. As part of the calculation, we take into account such activities as: reading the proper technological documentation, downloading and passing the tools and the necessary technological equipment, arming and disarming the machine tool, handling semi-finished products and processed products.

The contemporary nature of production means that the preparatory and completion time plays an important role in the organization of production. In the case of mass production, its existence was not so important.

The unit time is the time necessary to perform one technological operation on the workpiece or workpieces. The unit time t_j is the sum of the times t_w and t_u ie execution time (activities related directly to the execution of a given technological operation) and the complementary time (operation of the machining station, physiological needs of the operator).

where: t_j – unit time, t_w – execution time, t_u – supplementary time.

Fig. 2. An example of simultaneous processing of two workpieces (MT Poznańskie MACHTOOL 2016)

	The execution time is the sum of the times t_g and t_p, which is the main time and auxiliary time.
	The main time is the time in which the shapes, dimensions, or properties of the workpiece or the relative position and attachment of objects are changed (assembly operation). We distinguish: main machine, manual and machine-manual time – machining can be performed by machine (eg milling, turning) or manually (eg manual edge file machining, or manual deburring). Determining the main machine time is based on analytical calculations for individual technological treatments.
	Auxiliary time is the time necessary to perform the necessary repetitive activities repeated during a technological operation (machining or assembly) for each piece or piece of workpiece or several items without changes (as described at tan). These operations can be performed either by the operator or by the machine (automation of the machining station). Examples of actions are: basing and fixing, the workpiece, removing the workpiece, changing the machining parameters, other machining operations, measuring the workpiece both by the operator and the system with the objective probe.
	The supplementary time includes the service time t_o and the physiological time of the operator t_f. The service time includes activities related to maintaining the work station’s ability to work and these are tasks that are unique to any workpiece (or group of objects). The time of physiological needs is necessary to meet the physiological needs of the operator and maintain the ability to work.

where: t_o – service time, t_f – time of physiological needs. In the case of supplementary time here it is assumed that it is 12% of execution time t_w.

Service time refers to maintaining the capacity of the workstation to work and includes technical support time t_ot and organizational t_oo. Examples of actions taken into account during t_ot are: replacement of a blunt tool, removal of chips. The t_oo includes: undertaking, preparation of tools and their devotion after finishing work, submitting documentation and the workstation of another change.

where: t_ot – technical support (service) time, t_oo – organizational service time.

where: the value of the coefficient k_ot is taken as 3%

where: k_oo coefficient value is accepted from 6% to 9%

	Employee rest time – needed to be taken into account when the machine operation cycle alone does not provide this option.
	The time of natural needs – indispensable to the needs of the employee.
	The time of physiological needs is divided into the time of rest of the employee / operator and the time of physiological needs.

where: t_f – time of physiological needs, t_fn – time of natural needs, t_fo – time of rest of the employee.

where: the value of the factor kf is 0.02 which results from 2% of the time t_w

To sum up, the analytically determined standard of technological times (standard of working time) for serial production takes the following form:

where k_u – complementary time coefficient, other designations as above.

For mass production the standard of technological times is based on the formula:

The above method is an analytical method that allows for an acceptable estimation of the standard of working time (standard of technological times) for a given technological operation and a comprehensive technological process. The experimental method is also used, which consists in measuring individual activities in a given company at a given workstation during the implementation of various technological tasks.

Sources

Feld M., Podstawy projektowania procesów technologicznych typowych części maszyn, WNT 2000
Knowledge – dr inż. Jan Berkan (RIP 2018)
Own notes.
Staworzyński P., Techniki normowania czasu – www.staworzynski.boostnet.pl

About author

morek

Born 1973. In 1993, I graduated from Technical Secondary School No. 1. In 1998, the Faculty of Mechanical Engineering and Automation (now Faculty of Production Engineering) - Warsaw University of Technology. 1997-2000 cutting tools manufacturer at VIS Precise Products Factory S.A. 2004. Unfortunately, this company no longer exists. PhD in gear technology. Production technologies and technological processes are my passion.