Planning & Scheduling

Planning & Scheduling Summary Lectures 1+2

Planning & Scheduling

Aims to organize that the value proposition is reached efficiently and is feasible given the company’s capability. It addresses the organization of renewable resources (supply) based on customer demand (forecast) and process plan.

Manufacturing Planning and Control (MPC) algorithms

Aggregate planning (product-mix / workforce planning); Tactical planning (order acceptance, resource capacity loading); Operational planning (scheduling, shop floor control).

MRP systems

Material Requirement Planning (MRP I): Bill of material and lead time off-sets. Manufacturing Resource Planning (MRP II): Push system.

Advantages of MRP systems

Emphasis on bill of materials and dependent demand; Emphasis on information structuring.

Disadvantages of MRP systems

No finite capacity planning; Fixed, instead of workload-dependent lead times; Product characteristics must be known in advance; No capabilities to deal with uncertainty; Materials oriented, not process, not capacity.

MRP vs JIT Systems

MRP is a push system based on forecasts, where as JIT is a pull system based on demand.

Lead Time Syndrome

If lead time = backlog/capacity, and at some point, you cannot deliver what you expect to deliver the backlog and lead time increases. Customers order more, so backlog increases even more.

JIT/Kanban

Just-in-time (JIT) aims to meet demand exactly in time, quality and quantity. Kanban uses signs on the work floor to indicate when new materials are needed. Both are pull systems.

Advantages of JIT/Kanban

Simple logic, no computerization needed; Reduction of in-process inventories; Stable lead times.

Disadvantages of JIT/Kanban

Limited number of products allowed; Stable demand required and/or high technical flexibility; High line-reliability requested; Set-up times should be minor, or eliminated.

Workload control

Capacity-oriented planning system. Advantage: stable internal lead times. Drawback: no constant demand, customers have to wait. It ignores external delay times.

Hierarchy Production Planning (HPP)

Capacity-oriented planning system. Planning systems determined by: LP (product type level), knapsack-type allocation models (product family level) and run-out time based heuristic (item level).

Cyber-physical system

System in which a mechanism is controlled by computer-based algorithms, integrated via internet and its users. Consists of physical and software components (machines, factories, algorithms, computers, …).

Customer Order Decoupling Point (CODP)

A point in the manufacturing process where the trigger for production changes from forecast-based to customer-order based.

Aggregate Planning

Long-term planning (usually 1-2 years) that concerns staffing/workforce planning, product planning, procurement, subcontracting, and marketing.

Resource Loading / Rough Cut Capacity Planning (RCCP)

Occurs during order acceptance, determines when orders should be released for production, can delivery dates be met, how much operator & machine capacity required, and is irregular capacity (overtime work/subcontracting) required?

Technological Planning

Involves decisions about technology and infrastructure.

Resource Capacity Planning

Deals with renewable resources (e.g., people).

Material Coordination

Concerns nonrenewable resources.

OA (Order Acceptance)

Overloaded system (no resource flexibility) and unrealistic due dates (no time flexibility).

𝑀0

Set of Machines that are fixed schedules for a subset. M is the set of all machines.

α (Graham notation)

Machine environment from Graham Notation: Single-stage includes 1, P, Q, R and Multi-stage: O, F, J

β (Graham notation)

Job Characteristics and constraints from Graham Notation: 𝑝𝑖=𝑝, 𝑝𝑖=1, 𝑟𝑗, 𝑑𝑗,transportation delays (𝑡𝑗𝑘) etc.

γ (Graham notation)

Objective function with completion time (𝐶𝑗), flow time (𝐹𝑗), lateness (𝐿𝑗), throughput, tardiness (𝑇𝑗) and earliness (𝐸𝑗)

Renewable Resources (Project Scheduling)

Prespecified number of units of resource available for every period of planning horizon.

Non-renewable Resources (Project Scheduling)

Number of units of a resource is available for the entire planning horizon.

el (Operating room planning)

Elective patients in operating room planning, surgery can be planned in advance

nel (Operating room planning)

Non-elective patients in operating room planning → unexpected surgery and thus urgent

Access Policy for patients

Determines whether scheduled patients are pre-scheduled or same-day patients

Traditional (OAS)

Books patients in advance (disadvantage: no-show rates higher).

Open-access

Assigns all capacities to same-day appointments (disadvantage: daily fluctuations in demand lead to poor utilization and patient have booking preferences).

Hybrid access

Combination of traditional and open-access methods.

Strategic (OAS decision type)

Long-term decisions that determine the main structure of an AOS.

Tactical (OAS decision type)

Medium-term decisions related to how patients as a whole are scheduled.

Operational (OAS decision type)

Short-term decisions concerned with scheduling individual patients.

Rule-based approach (RBA)

Provides set of easy-to-implement instructions (heuristic) to determine operational decisions.

Optimization-based approach (OBA)

Specifies optimal level for an operational decision.

Material planning

Acquisition, storage, distribution and retrieval of all consumable resources/materials

Ambulatory care services

Care without room, bed, and board

Emergency care services

Evaluation and initial treatment of urgent and emergent medical problems

Surgical care services

Operative procedures diagnosis and care

Inpatient care services

Hopitalized patients with room, bed, and board

Home care services

Community health and nursing services providing multiple, coordinated services to a patient at home

Residential care services

Supervision and assistance in activities of daily living with medical and nursing services

Cyclic Appointment Schedule (CAS)

Specifies capacity cycle (max number of patients scheduled on each day of a cycle) and day cycle (max number of patients to be scheduled per time slot on each day).