Design for manufacture through fabrication : a manufacturing time and cost estimation model for large fabricated assemblies

De Swardt, A. V. (1998)

Thesis (Meng)--University of Stellenbosch, 1998.

Thesis

ENGLISH ABSTRACT: This thesis concerns the development of manufacturing time and cost estimation models for large mechanical engineering assemblies. The objective of the time and cost models are to serve the design engineer as a tool for estimating manufacturing time and cost, as the design progresses from the conceptual to the detail design stage. The manufacturing time and cost estimation models will give the designer the advantage of evaluating different concepts with time and cost as decision making criteria. The models can also be used as a redesign tool for existing products so that a cost comparison can be made between the existing and new design. The models can also be used as a design optimisation tool for the manufacturing time and cost of a new design or redesign. This will reduce unnecessary costs associated with a certain design Basic process flow diagrams were determined from shop floor practice for each manufacturing process and its secondary process( es). Data for these models were obtained by time studies. The time study data was then used to investigate correlation's between manufacturing time and certain design parameters. Manufacturing time estimation formulae were then developed from the time study data. Five major time and cost estimation models were developed and tested. The five models are: Welding Time Estimation for the Flux Core Arc Welding Process, Tack Welding Time Estimation, CNC Flame Profile Cutting Time Estimation, Manual and Mechanised Bevelling Time Estimation and Plate Bending Time Estimation. Each model depicts the manufacturing time and consumable requirements.

AFRIKAANSE OPSOMMING: Die tesis hand el oor die ontwikkeling van 'n model vir die vervaardigingstyd en kosteskatting van swaar meganiese ingenieurstrukture. Die hoofdoel van die model is om 'n gereedskapstuk te wees vir die ontwerpingenieur, waarmee hy die vervaardigingstyd en -koste kan skat vanaf die konsepontwerp tot en met die detailontwerp. Die model sal die ontwerpingenieur daartoe instaat stel om twee konsepte teen mekaar op te weeg ten opsigte van vervaardigingstyd en -koste. Dit kan ook gebruik word as 'n herontwerp gereedskapstuk vir bestaande produkte, sodat die nu we ontwerp teen die oue opgeweeg kan word. Die model kan verder gebruik word as 'n ontwerp-optimeringsgereedskapstuk vir beide 'n nuwe en herontwerp. Dit sal lei tot die eliminering van onnodige vervaardigingskostes van 'n spesifieke ontwerp. Basiese prosesvloeidiagramme is opgestel vir elke vervaardigingsproses uit algemene werkwinkelpraktyk. Prosesvloeidiagramme is ook opgestel vir die sekondere vervaardigingsprosesse. Tydstudiedata is opgeneem vir elke vervaardigingsproses en die gepaardgaande sekondere proses(se). Korrelasies tussen beskikbare ontwerpparameters en vervaardigingstye is ondersoek met behulp van die tydstudiedata. Vervaardigingstyd skattingsformules is ontwikkel uit die tydstudiedata. Vyf hooftyd en kosteskattingsmodelle is ontwikkel en getoets. Die modelle sluit in: sweistydskatting, geoutomatiseerde gasvlamsny, afskuinsing van plaatonderdele vir sweisvoorbereiding, plaatbuig en vashegtingsweis van onderdele. Elke model weerspieel die vervaardigingstyd en materiaalbenodigdhede. Page

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/50928
This item appears in the following collections: