Manufacturing Method

Abstract

A method of manufacturing metal components and sub-assemblies from sheet material includes assessing incoming jobs to be carried out over a predetermined time period and assessing stock sheet material

Description

FIELD OF THE INVENTION This invention relates to a manufacturing method and in particular to a method of manufacturing metal components and sub-assemblies from sheet material. BACKGROUND OF THE INVENTION In manufacturing, scheduling systems are used to determine an efficient distribution of manufacturing jobs among available resources to minimise the average completion time by balancing the workload of machines. It is of vital importance to schedule manufacturing and fabrication jobs as efficiently as possible. An efficient schedule increases production capacity, speeds up completion of orders, and reduces costs. However, when orders are taken for multiple different manufacturing jobs, it is known to be a computationally difficult problem to schedule a large number of manufacturing jobs in an optimal or near-optimal way. Many parts are cut from sheet metal of various thicknesses before forwarding to subsequent work stations for subsequent manufacturing steps, such as folding, drilling and welding. The cutting and knocking out of parts from stock sheet material and the subsequent organisation of the parts for transfer to subsequent manufacturing stations is traditionally a time consuming and labour intensive process and the optimisation of this cutting stage is important for reducing material cost. Determining raw material requirements, particularly sheet metal, is also a problem, usually requiring a large stock of different thickness and grades of sheet metal to be retained to ensure that sufficient stock materials are available, when required. The variable material costs and material demand required for a particular job is also difficult to determine when providing a customer with an estimate of the cost of a particular job. SUMMARY OF THE INVENTION 03 07 25 According to the present invention there is provided a method of manufacturing metal components and sub-assemblies from sheet material comprising the steps of 5 assessing a plurality of incoming jobs to be carried out over a predetermined time period, including assessing stock sheet material requirements for said plurality of jobs, in terms of material dimensions, thickness and material grade, and assessing required manufacturing operations at a plurality of different operation stations for said plurality of jobs, scheduling the required operations and stock material 10 requirements and determining a schedule of operations so that the plurality of jobs can be carried out substantially simultaneously, said method including the step of sorting parts from said plurality of jobs based on thickness and grade of stock sheet material from which each part is to be cut and spatially arranging the sorted parts on respective stock sheets in an optimised manner, wherein each separate part of 15 each of said plurality of jobs is given a unique identifier, and including the step of cutting out the parts based on the determined optimised spatial arrangement of parts on each sheet and knocking them out from the respective stock sheet, wherein said unique identifier is etched onto each part as it is cut out from a respective stock sheet, and wherein each separate part is also etched with a 20 visually discernible identifier identifying the next operation station to which the part is to be delivered after knocking out the parts from the sheet, once cut and etched. Each part may be allocated a part deadline by which deadline it is required to be cut to meet a required manufacturing schedule, said step of sorting parts from said 25 plurality of jobs and spatially arranging parts on respective stock sheets utilising said part deadlines to ensure that parts are available for further operations and to ensure that jobs are completed by the required deadlines while maximising stock material usage. 30 Each separate part may be etched with an identifier indicating the total number of the respective separate parts being cut from the respective stock sheet (i.e. total number of a respective part required for a respective job or group of jobs). Preferably a unique identifier is assigned to one or more remainders / remnants of each stock sheet (i.e. the material remaining after optimising the spatial arrangement of the sorted parts on respective stock sheets) said identifier including information regarding dimensions, thickness and grade of the respective remnant, said information being stored and the remnants identified as stock material available when subsequently spatially arranging parts on respective stock sheets, including said remnants, thereby further reducing waste and reducing material cost for a given job. The unique identifier for each remnant may be assigned during the programming / spatial optimisation stage, prior to cutting the stock sheet. A label may be printed and applied to each remnant at a part separation stage. The manufacturing operations carried out at respective operation stations may include folding and bending selected parts, drilling selected parts, sorting selected parts into kits for assembly into sub-assemblies, welding selected parts and subassemblies, and coating and finishing selected parts. In one embodiment a label may be applied to at least some of the parts (for example to at least one part of each group of identical parts), said label including the respective part’s unique identifier as well as a job identifier for the particular job to which the part belongs, part dimensions and a visual representation of the part, the identifiers etched onto each part being used to determine the correct label to be applied to a respective part after knocking out. Parts upon which a particular manufacturing operation is to be carried out may be sorted and collated onto a common carrier utilising information provided on said part labels and / or identifiers etched onto the respective parts. Each common carrier may include an identification label containing information identifying the respective common carrier. The common carriers may comprise pallets or trolleys. The labels applied to said parts and to said common carriers may include a scannable or otherwise machine readable marking, such as a barcode. Each operation station may be provided with a machine readable identifier so that the location of each labelled part and each common carrier can be recorded and monitored throughout the manufacturing system. Each common carrier may be transferred to and from specific operation stations at which the or each required operation is carried out in accordance with the determined schedule of operations based on information associated with the labels of the parts located thereon and / or the label of the respective common carrier. Preferably a storage system is provided within which stock sheet material is stored and within which said common carriers can be located. Preferably parts, once fabrication and finishing operations are completed, are sorted and collated in accordance with the specific jobs to which they relate, preferably based upon information provided on the labels. The manufacturing method is preferably carried out under control of a computer control system programmed to assess said material requirements for said plurality of jobs and said required operations at said plurality of different operation stations for said plurality of jobs and to nest the required operations for all of said plurality of jobs and to allocate said unique identifier to each part. The computer control system may be programmed to control movement of parts between operation stations and provide instructions to operators at each operation station to achieve the determined schedule of operations based on the unique identifier and / or label applied to each part. The step of assessing a plurality of incoming jobs to be carried out over a predetermined time period may also determine a cost of each job based on the determined material requirements and required manufacturing operations, such cost being available to provide a customer with an accurate quotation for the cost of a particular incoming job. BRIEF DESCRIPTION OF THE DRAWINGS A system for carrying out a manufacturing method in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a manufacturing method in accordance with an embodiment of the present invention; Figure 2 is a schematic illustration of raw material utilisation process of the method of Figure 1; Figure 3 is a schematic illustration of a method of handling remnants of material after parts have been cut out of the material to allow the remnants to be made available for subsequent parts; and Figure 4 is a schematic view of operations carried out on parts in the manufacturing method of Figure 1 following cutting and separation of parts from sheet material. DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 shows a flow chart illustrating the operation of the manufacturing system in accordance with the above described embodiment of the invention. A system for carrying out a manufacturing method in accordance with an embodiment of the present invention is computer controlled, the computer control system incorporating algorithms to optimise raw material usage, part handling and manufacturing and fabrication operations for a plurality of jobs whereby said jobs are scheduled to be carried out simultaneously. The nesting of parts produced from sheet material, using program software in conjunction with a production schedule with links to stock management of an automated storage system, optimises material requirements and minimises manufacturing time. Parts are cut from selected stock sheets by a laser cutter and at the same time parts are etched with respective unique identifier information that allows for swift collation and transfer of parts to their next process. An automated storage system is used to store stock raw materials and to return work in progress (WIP) parts before they are conveyed to their next process under the control of the production schedule. In particular the computer control system is programmed to provide optimised nesting of parts of said plurality of jobs required to be cut from sheets of stock material of a required thickness to optimise material usage and minimise waste by fitting the maximum number of parts on a stock sheet of given thickness and material. By nesting the plurality of jobs in this way, parts of said plurality of jobs to be cut from a specific thickness of sheet material are arranged on respective sheets by the computer control system in an optimised manner to minimise unused material and minimise material wastage. The required stock metal sheets may be obtained / ordered once the nesting process is complete, minimising the amount of stock raw materials that must be stored at any given time. Parts may be nested based on required material thickness and material grade and deadline (date / time) at which parts are required to at respective operation stations to comply with the determined manufacturing schedule, thereby providing balance between raw material utilisation and production flow. Once each stock sheet has been used, the control system immediately adjusts the record of the remaining stock level within the automated storage system. The computer control system is programmed to provide optimised nesting of parts on respective stock sheets based on required material thickness and grade and “cut-by” date (latest date at which the part is required to enter the manufacturing system to meet the manufacturing schedule). A balance can be struck based on “cut-by” date and raw material utilisation for a given job. Jobs are multi-nested together, rather than completed on a sales order basis. Once nesting is complete, raw material can be ordered as required to meet material demand. Once delivered, this raw material is stored within the automated storage system ahead of cutting. Once cutting is due to occur, a control program is loaded to the laser cutter and the required stock sheets are automatically delivered to the laser cutter from the automated storage system. The nesting of parts on a particular stock sheet of specific thickness and grade is carried out based on data including the dimensions and shape of the required parts for a plurality of jobs required to be completed over a predetermined time period and based on a deadline for each part to be completed within a given time frame imposed by the manufacturing schedule, the nesting program iteratively nesting parts on a respective stock sheet of a predetermined material and thickness until a predetermined minimum (percentage) of unused material is determined or until a time is reached determined necessary to achieve the required availability deadline for all available parts to be nested, whereupon the nesting program is finalised and sent to the laser cutter for the cutting operation to begin (as schematically illustrated in Figure 2). During the cutting process, each part is etched with a respective part number, total quantity of respective parts required for said production order number and a letter code identifying to the next immediate process for each part after part separation / knocking out. This is to improve the efficiency of the Part Separation process. Such code may be etched directly onto each part at the same time as it is cut and may also be applied to a label attached to each part. This “next immediate process” information may be being indicted by a letter, to improve the efficiency of part separation process, such as: S - Small Fold M - Medium Fold L - Large Fold XL - Extra Large Fold D- Drill / Tap / CSK H - Kit HLC K - Kit Main Site F - Kit Front Module P - Powder Coat E - Ecoat Z - Zinc G - Galv Each part is allocated a unique identifier by the computer control system in the form of an identification code, etched onto each part during cutting. The unique identifier may be constructed from a production order number and line number. In a preferred embodiment, each part may be etched with a unique part identifier, a code (e.g. letter) indicating the next process after Part Separation and the total number of that particular part required for the respective job. Once nesting of parts in a respective sheet has been completed, the unused parts of each sheet, referred to as “remnants” are identified and each remnant is allocated an unique identifier, identifying each remnant and including information regarding dimensions, thickness and material grade. The remnants, or at least remnants greater than a predetermined size, may then be identified as available stock material and returned to store, preferably labelled or etched with a respective unique identifier, and made available for subsequent use as raw material for cutting out subsequent new parts. This process is illustrated in Figure 3. During the process of nesting parts on a sheet, parts may be arranged on the sheet to maximise the size of any remnants. Remaining portions of the sheet below a predetermined size considered to be useful as a remnant may be rejected as scrap rather than being retained as a useable remnant. A label may be applied to each separate part (or at least one of a group of identical parts) following cutting and knocking out. The label may contain a number of pieces of information about the part, such as the part’s unique identification code, a part number for the part, an indication of the next operation to be carried out on the part after knocking out, the dimensions of the part and a visual representation of the part to facilitate correct labelling and identification of the part, the total number of respective individual part of a specific types required for the job or group of jobs as well as the specific job to which the part belongs and a machine readable marking to allow details of the part to be scanned by the computer system at various locations as the part moves through the manufacturing system. Information on the label may include part number, quantity of specific parts required for production order number, 2-D visual image of the respective part, part dimensions, part weight and 2-D barcodes for scanning at each process. Sorted parts may be moved between operation stations of the manufacturing system on common carriers in the form of pallets or trolleys. The labels applied to the trolleys or pallets may identify where the parts located thereon need to go to after cutting out. For example, ‘S’ may indicate small parts, all these parts will be on one pallet and go to one press machine. The parts are sorted and placed on selected pallets or trolleys in accordance with the information etched onto the parts and / or on their labels. Parts loaded onto pallets can be returned to the automated storage system and can be later called upon when their next process is due for completion. Trolleys are moved and scanned to their next location. The storage system is used to store stock raw sheet material ahead of cutting. Once laser cutting / etching of parts has been completed, the processed sheets may be stored back within the automated storage system until they are due for part separation / knocking out. Each operation station (as well as any storage locations wherein parts are to be held) also preferably has a machine readable label associated therewith that can be scanned at the same time as pallets or trolleys arrive at such locations so that the location of parts can be tracked and monitored throughout the manufacturing operation at all times. The scanning of the label of a trolley or pallet upon arrival at a particular operation station may prompt the computer control system to provide the operator at such operation station with information regarding the required operations to be carried out on the parts, including the number of parts upon which said operation is to be carried out. The operator may interact with the computer control system to record completed operations. The computer control system may also record the identity of the person who carried our particular operations, for example for future quality control and training purposes. The use of an control system / schedule will create a demand on raw material which is purchased ahead of cutting time based on what sheets have been programmed for each material thickness. With the assistance of a part label, parts movement through the manufacturing process are tracked, along with a status update on each part and what processes the part has currently completed. Operators will have access to work instructions to completed works at each process of the part. Again, schedule drives when each process should be completed. The manufacturing system includes a storage system incorporating racking adapted to hold and control raw materials (i.e. stock metal sheets of various material, size and thickness) as well as parts after being cut out on a laser cutting system. The storage system is controlled by the computer control system and incorporates conveying devices, including one or more cranes and belt or roller conveyors, adapted to move selected pallets into and out of the racking and to and from a knocking out station or part sorting region. In one embodiment the storage system may comprise twenty storage towers, each tower having a possible twenty four locations, each location having a unique identifier, for example comprising a four digit number, wherein the first two digits relate to the tower and the second two digits relate to the location within the tower. In the example, code “0712” indicates that the selected pallet is located in rack twelve of tower seven. A laser cutter is provided having at least one cutting bed upon which a selected stock sheet of a selected material and thickness may be placed and a laser used to cut out selected parts from the selected stock sheet. The storage system is preferably adapted to automatically transfer stock sheets of selected thickness and material from the racking to the at least one cutting bed and back into the racking or onward towards selected operator stations under control of the computer control system, enabling this process to be fully automated without requiring the operator to manually load stock sheets onto and off the or each cutting bed. Manufacturing operations carried out on the cut parts can include CNC machining, folding, bending, drilling, fabrication kitting and welding, coating and finishing. The label on a given part and the labels on each pallet or trolley are repeatedly scanned during movement of the parts and pallets and trolleys throughout the system so that the computer control system can track each part throughout the system. Pallets or trolleys of parts are transferred to the relevant operation station and the computer control system is preferably programmed to provide instructions to the operator in respect of the operations to be carried out, based on the information on the pallet label and the label of each part. Once the required operations have been completed the parts are again scanned and may be returned to the pallet or trolley for onward travel to the next required process. Once all operations have been completed the pallets or trolleys of parts may be transferred to a sort area where parts can be sorted, under instruction from the computer control system and based on the scanned labels, to collate parts for each individual job. The collated parts of each job may be placed on one or more pallets or trolleys, labels being printed and applied thereto to identify each job before the collated parts and / or sub-assemblies for each job are moved to a respective storage region for despatch to the customer. At each manufacturing stage, quality checks may be undertaken by operators, preferably under instruction of the computer control system. At the initial programming stage, jobs are reviewed to determine material requirements and common parts are nested in sheets of common thickness and material to maximise material utilisation and minimise wastage. The parts are sorted based on thickness of material from which the part is to be cut and then spatially arranged on respective sheets within the software to maximise usage of said sheets and minimise wastage. The computer system allocates a unique identifier to each part as well as identifying a part number and other information regarding the operations to be carried out on each part, the number of parts to be produced and other information linking the part to a specific job. The raw materials required are then determined, purchased and delivered and loaded into the storage system. The information from the initial programming stage is then used to control the laser cutter and the storage system to transfer the required material from the storage system onto the appropriate bed of the laser cutter and operate the laser cutter to cut out the parts as well as etch each part with its part number. After the cutting operation has been completed, the cut sheet is moved to a part separation stage, where the parts are knocked out (separated) from the sheet, and labels may be applied to at least some of the parts, based on the information etched onto each part, before the parts are sorted and placed on selected pallets or trolleys based on information applied to each part, etched onto each part and / or included on the part’s label, identifying the next operation to be carried out on the respective part, before the pallets or trolleys of sorted parts are transferred to the next operation and / or moved back into the storage system as a buffer before being moved on to the appropriate operation station. The labels on parts and the label on each pallet or trolley are scanned at each operation station / location to trace the location and movement of each part through the manufacturing system. Kits of parts required for a subassembly may have a common label indicating such. As illustrated in Figure 4, each pallet or trolley of parts may be moved through different operation stations, such movement being determined by the label and / or etched identifier on each part and / or the label on each pallet or trolley. The operation stations shown in Figure 4 comprise a drilling stage, wherein parts that require drilling are drilled as required; one or more folding stages, wherein parts requiring folding are folded on a press; one or more bending stages, wherein rollers are used to form bends in parts; a kit sort stage, wherein parts to be assembled together as sub-assemblies, by welding or other fastening methods, are collated before the selected parts are transferred to a fabrication stage for welding or other assembly processes; a finish stage, wherein parts that require a specific surface finish, such as painting or galvanising, are processed; and a despatch stage, wherein parts are sorted and collated into the relevant customer orders for each respective job. The manufacturing system of the present invention, through the computer control of the storage system, laser cutter and the scheduling of manufacturing operations, and by providing unique identification codes and identification labels for each part that allow the parts to be tracked throughout the manufacturing system and which provide instructions for the movement of parts though the manufacturing system and the nesting of parts from several different jobs, facilitates optimisation of material usage and optimisation of operating capacity of each operation station, thereby overcoming the problems encountered with known manufacturing systems. The invention is not limited to the embodiment described herein but can be 5 amended or modified without departing from the scope of the present invention as defined by the following claims.

Claims

03 07 251. A method of manufacturing metal components and sub-assemblies from sheet material comprising the steps of assessing a plurality of incoming jobs to be carried 5 out over a predetermined time period, including assessing stock sheet material requirements for said plurality of jobs, in terms of material dimensions, thickness and material grade, and assessing required manufacturing operations at a plurality of different operation stations for said plurality of jobs, scheduling the required operations and stock material requirements and determining a schedule of 10 operations so that the plurality of jobs can be carried out substantially simultaneously, said method including the step of sorting parts from said plurality of jobs based on thickness and grade of stock sheet material from which each part is to be cut and spatially arranging the sorted parts on respective stock sheets in an optimised manner, wherein each separate part of each of said plurality of jobs is 15 given a unique identifier, and including the step of cutting out the parts and knocking them out from the respective stock sheet based on the determined optimised spatial arrangement of parts on each sheet, wherein said unique identifier is etched onto each part as it is cut out from a respective stock sheet, and wherein each separate part is also etched with a visually discernible identifier identifying the next operation 20 station to which the part is to be delivered after knocking out the parts from the sheet, once cut and etched.

2. A method as claimed in claim 1, wherein each part is allocated a part deadline by which deadline it is required to be cut to meet a required manufacturing 25 schedule, said step of sorting parts from said plurality of jobs and spatially arranging the sorted parts on respective stock sheets utilising said part deadlines to ensure that parts are available by the respective deadlines while maximising stock material usage.30 3. A method as claimed in any preceding claim, wherein each separate part is etched with an identifier indicating the total number of the respective separate parts being cut from the respective stock sheet.03 07 254. A method as claimed in any preceding claim, wherein a unique identifier is assigned to remnants of each stock sheet after optimising the spatial arrangement of the sorted parts on respective stock sheets, said identifier including information regarding dimensions, thickness and grade of the respective remnant, said 5 information being stored and the remnants being identified as stock materialavailable when subsequently arranging parts on respective stock material.

5. A method as claimed in any preceding claim, wherein said manufacturing operations carried out at respective operation stations include folding and bending 10 selected parts, drilling selected parts, sorting selected parts into kits for assembly into sub-assemblies, welding selected parts and subassemblies, and coating and finishing selected parts.

6. A method as claimed in preceding claim, wherein a label is applied to at least 15 some of the parts, said label containing the respective part’s unique identifier as well as a job identifier for the particular job to which the part belongs, part dimensions and a visual representation of the part, the identifiers etched onto each part being used to determine the correct label to be applied to a respective part after knocking out.

207. A method as claimed in claim 6, wherein parts upon which a particular manufacturing operation is to be carried out are sorted and collated onto a common carrier utilising information provided on said part labels and / or identifiers etched onto the respective parts.

258. A method as claimed in claim 7, wherein each common carrier includes an identification label containing information identifying the respective common carrier.

9. A method as claimed in claim 8, wherein the label applied to the parts and to the 30 common carriers includes a scannable or otherwise machine readable marking, such as a barcode.03 07 2510. A method as claimed in claim 9, wherein each operation station is provided with a machine readable identifier so that the location of each part and each common carrier can be recorded and monitored throughout the manufacturing system.5 11. A method as claimed in claim 10, wherein each common carrier is transferred to and from specific operation stations at which the or each required operation is carried out in accordance with the determined schedule of operations based on information associated with the labels of the parts located thereon and / or the label of the respective common carrier.1012. A method as claimed in any of claims 7 to 11, wherein a storage system is provided within which stock sheet material is stored and within which said common carriers can be located.15 13. A method as claimed in any of claims 7 to 12, wherein parts, once fabrication and finishing operations are completed, are sorted and collated in accordance with the specific jobs to which they relate, based upon information provided on the labels.20 14. A method as claimed in any preceding claim, wherein the manufacturing method is carried out under control of a computer control system programmed to assess said material requirements for said plurality of jobs and said required operations at said plurality of different operation stations for said plurality of jobs and to nest the required operations for all of said plurality of jobs and to allocate25 said unique identifier to each part.

15. A method as claimed in claim 14 when dependent upon claim 6, wherein the computer control system is programmed to control movement of parts between operation stations and provide instructions to operators at each operation station to 30 achieve the determined schedule of operations based on the unique identifier and / or label applied to each part.

16. A method as claimed in any preceding claim, wherein the step of assessing a plurality of incoming jobs to be carried out over a predetermined time period alsoLO CXIdetermines a cost of each job based on the determined material requirements and required manufacturing operations, such cost being available to provide a customer with an accurate quotation for the cost of a particular incoming job.5 17. A method as claimed in any preceding claim, wherein said visually discernible identifier identifying the next operation station to which the part is to be delivered comprises a letter code.

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