Tightening Process Research Articles

Investigation of maximum torque values in manual tightening of dental implant healing screws

Aims: This study aimed to investigate the change of the maximum torque values applied by the dentist according to the parameters of gender,dental experience and glove type used in the tightening processes applied manually by pre-graduated and post-graduated dentists to the implant superstructure parts. Methods: 24 dentists (11 Male, 13 Female) participated in our study.Participants were instructed to tighten the implant healing screw (Straumann Dental Implant System, Waldenberg, Switzerland) placed on the digital torque measuring device(Cap torque tester series TT01; Mark10, Copiague, NY)by applying maximum force with a manual wrench.Powdered latex gloves,powderfree latex gloves and sterile surgical gloves were made available to the participants in order to imitate the mouth conditions as much as possible.Manual tightening was repeated three times in each group,with at least three minutes duration. Data were recorded digitally and statistical analysis was performed with IBS SPSS statistics 22 program.Independent sample t-test and one-way Anova analysis were used to evaluate differences between groups, followed by the post-hoc Tukey test. Results: Maximum torque value for tightening with powdered latex gloves (20.01±5.55) N, powder free latex gloves (17.27± 4.34) N and surgical gloves (20.27±6.02) N was found.In addition, we did not find a statistically significant difference in terms of gender and dental experience,which are the other parameters we investigated. Conclusion: Gender, experience and glove type do not statistically affect the maximum torque to be applied in implant superstructure applications.

Analysis and determination of bolt tightening process factors for composite structures under multiple working conditions

When developing the tightening process for composite bolts, ensuring that the target preload( F) required by design is achieved is a key scientific issue in meeting the mechanical properties of the connected structure. Variations in complex process factors during tightening have a large effect on the tightening torque( T)-preload curve( F), and the mechanism by which the tightening process factor affects the target preload must be considered. Using experimental means, the significance and coupling effects of tightening speed, lubrication conditions, tightening areas, joint sealants and washers have been systematically investigated. The tightening torque( T), torque coefficient( K), preload( F) and the peak stress coefficients X( σ) and interlaminar stress coefficients Y( σ) within the composite laminate are used as the main response variables, and a mathematical model between each response variable and the process factor is established to analyse the effect of significant factors on the response variables from a quantitative perspective. Finally, with a certain size of preload( F) as the optimisation target, the optimisation analysis of the tightening speed is carried out for four working conditions with different sealing conditions and different tightening area, and the optimum tightening speed for each working condition is determined. Based on the above study, an analytical method was proposed to determine the reasonable interval of tightening process parameters in this paper.

Research on Assembly Method of Threaded Fasteners Based on Visual and Force Information

Threaded fastening operations are widely used in assembly and are typically time-consuming and costly. In low-volume, high-value manufacturing, fastening operations are carried out manually by skilled workers. The existing approaches are found to be less flexible and robust for performing assembly in a less structured industrial environment. This paper introduces a novel algorithm for detecting the position and orientation of threaded holes and a new method for tightening bolts. First, the elliptic arc fitting method and the three-point method are used to estimate the initial position and orientation of the threaded hole, and the force impact caused by switching from the free space to the constrained space during bolt tightening is solved. Second, by monitoring the deformation of passive compliance, the position information is introduced into the control process to better control the radial force between the bolt and the threaded hole in the tightening process. The constant force controller and orientation compliance controller are designed according to the adaptive control theory. A series of experiments are carried out. The results show that the proposed method can estimate the initial position and orientation of an M24 bolt with an average position error of 0.36 mm, 0.43 mm and 0.46 mm and an orientation error of 0.65°, 0.46° and 0.59°, and it can tighten the bolt with a success rate of 98.5%.

Research on Prediction Method of Bolt Tightening for Aviation Components Based on Neural Network

Aviation components play an important role in national defense and aviation development. Bolt connections are widely used in the assembly of aviation components, due to their simple structure and convenient disassembly. In addition to the impact of elastic interaction, the gap between the tightened parts also makes it very difficult to obtain a uniform bolt load, to achieve the required tightness during the tightening process. However, the impact of elastic interaction can be reduced by selecting the best tightening sequence, and the optimal tightening sequence of aviation components under different gaps can be predicted by constructing a neural network surrogate model. Based on the predicted optimal sequence, the elastic interaction matrix corresponding to the sequence can be obtained. In order to obtain a uniform preload, the initial load of each bolt is calculated according to an elastic interaction matrix. This research has improved the tightness of aviation components and the real-life efficiency of tightening process planning.

A model on stitch tightening process of lockstitch machine

A model of stitch tightening process in lockstitch machine is formulated to predict the needle thread peak tension during stitch tightening and the position of needle and bobbin thread crossover point i.e. y-value. This y-value is then used to predict the thread consumption in a lockstitch seam. A computer program in C language is developed based on the model formulated in lockstitch machinery to predict needle thread stitch tightening tension and the position of needle and bobbin thread crossover point i.e. y-value. The developed model is validated qualitatively by studying the effect of different variables on peak value of needle thread tension. The model is also validated quantitatively by comparing the experimental and predicted values of peak tension and stitch length. A satisfactory predictive power of the model is observed which validates the developed model.

An improved 3D model of composite bolted joints with detailed thread structure and progressive damage analysis of realistic tightening process

Bolted joint is a common connection method in composite structure assembling. The initial assembly state has a significant influence on the subsequent performance. To realize the simulation of the assembly process of composite bolted joints, an improved 3D model is proposed. This model considers the detailed thread structure and can be used to simulate the realistic tightening process. The relationship between the tightening torque and bolt tension is analyzed and the effect of the friction coefficient on the value of the tightening coefficient is analyzed using this model. A new fitting model for the nonlinear pressure distribution state on the outer surface of the composite laminates during the assembly process is proposed. And a quantitative analysis and prediction method of the nonlinear pressure distribution state is established. Finally, the effects of bolt tension and washer type on initial assembly damage are analyzed and experimentally verified.

ITER Central Solenoid Precompression Test Mock-up – Validation phase to prepare the assembly on-site

The Central Solenoid (CS) is a key element of the ITER Magnet system, including six identical coils, called modules, assembled together to form a 4 m outer diameter, 13 m high solenoid. It is a superconducting magnet, with a peak field up to 13 T. The magnet is enclosed inside a steel structure providing vertical pre-compression and mechanical support. The room temperature pre-compression load is necessary to prevent displacement and gap between coils during the exploitation phase and therefore reduce the CS performance and create mechanical stress. The target CS pre-compression is 210 MN realized by the tightening of 45 Multi Jack Tensioners (MJTs) divided in 9 sectors. Procurement of the components and the procedures of the ITER CS is the responsibility of the USA Domestic Agency (USDA), while the ITER Organization (IO) will carry out the assembly of these components.IO signed in 2018 a collaboration agreement with CEA/IRFM to implement the pre-compression procedure proposed by the USDA using a dedicated mock-up with the main objectives:- Simulating the all modules stack rigidity with Spring plates;- Characterize the young's modulus of one CS section module;- Validating the technical procedures proposed- Estimating the time impact to accomplish the CS pre-compression process in accordance to the complete ITER Tokamak assembly.The CS mock-up Pre-compression Verification (CSPV) uses a 1/9 segment of the overall CS with a mix of ITER Tokamak and mock-up components. The target load of the mock-up is 23.3 MN to be in accordance with the overall CS pre-compression load value.This paper presents the CSPV mock-up activities, the challenges encountered and the results gained.As a conclusion, the tightening process is highlighted to estimate its applicability for the ITER CS assembly in term of technical and organisational aspects.The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

Tight power and energy coupling constraints of energy storage resources for unit commitment

AbstractEnergy Storage Resources (ESRs) can help promote high penetrations of renewable generation and shift the peak load. However, the increasing number of ESRs and their features different from conventional generators bring computational challenges to operations of wholesale electricity markets. In order to improve the computational efficiency, this paper tightens the generic ESR formulation for unit commitment. To avoid the complexity caused by ESR operations in both discharge and charge directions, a novel “decoupled analysis” is conducted to analyze one direction at a time. For each direction, ESRs over two and three time periods are categorized into several types based on their parameters. For each type, our recent four‐step systematic formulation tightening approach is used to construct the corresponding tight formulation. In order to consider more periods without analyzing all the drastically increased number of types, a series of major types are selected based on how many periods an ESR is able to discharge (charge) consecutively at the upper power limit. A related generic form of tight constraints over multiple periods is established. Moreover, validity and facet‐defining proofs of our tight constraints have been provided. Numerical testing results illustrate the tightening process and demonstrate computational benefits of the tightened formulations.

Research on the relationship between the tightening torque and the preload of composite bolted structures

Bolted joints are widely used in assembly of composite structures that transmit large loads. The relationship between torque ( T) and preload ( F) is needed to be obtained when using the torque method to tighten bolts. In this paper, the T- F relationship in the process of bolt tightening composite laminates was analyzed through bolt tightening experiments. The variation behavior of friction coefficient in this process was also studied. On this basis, a progressive damage finite element model was established using the improved LaRC05 criterion to analyze the stress and damage of the composite laminate during tightening. The various stages in the bolt tightening were divided and the mechanical properties of each stage were analyzed. The results of the study showed that the thread friction coefficient μth and the bearing friction coefficient μb change with the preload during the tightening process. Its behavior can be described using an exponential function. Serious stress concentration and assembly damage can be formed in the direct extrusion area of the outer edge of the locknut when the composite laminate is bolted. The bolt tightening process of composite laminates can be divided into five stages. Research conclusions are valuable for understanding composite structures and formulating the bolt tightening process.

Noncontact measurement of bolt axial force in tightening processes using scattered laser ultrasonic waves

This paper presents a new methodology for noncontact measurement of the axial force of bolts in their tightening processes using laser-generated ultrasound waves. This method employs ultrasound waves scattered in a bolt shaft to detect axial force changes, while most conventional ultrasonic methods use ultrasound waves propagating linearly along the bolt axis. The ultrasound waves in this study are generated by laser irradiation on the top surface of a bolt. Subsequently, they propagate deeply into the shaft and return towards the top of the bolt through complicated paths due to the multiple scattering in the shaft. Finally, they are detected at the top surface using another laser and a speckle knife edge detector. With an examination based on the acoustoelastic theory and finite element analysis, we demonstrate that the waveform of the scattered ultrasound shifts linearly with axial force by the cross-correlation method. The proposed technique does not require machining to flatten a bolt's head and the end, while conventional ultrasonic methods need flattening procedures. The proposed technique enables fast, cost-effective axial force measurement in mass production manufacturing processes.

A strength prediction of joints by Fe-Mn-Si-Cr shape memory alloy through strain monitoring during pre-processes including diameter expansion and tightening by heating

To guarantee the functionality of the pipe joint in different service environments, the evaluation of its strength is critical. Typically, the assessment is performed after completing the pipe joint assembly. However, it is pretty inconceivable to examine each pipe joint’s strength in the environment for actual installations. Therefore, a strength prediction of pipe joints is required as similar to the bolted-flange systems. Due to the unique manufacturing process of the pipe joint made of shape memory alloys (SMAs), the strength prediction before the installation becomes possible by means of its pre-processing. This work chooses the pipe joint made of the iron-based shape memory alloy (Fe-SMA), which is very promising in the joint families in SMAs because of its low weight. In the diameter expanding process of the Fe-SMA hollow cylinder with different methods, both the circumferential and axial strains are measured. After heating, the cylinder tightens round bar or pipes made of SUS304 due to the shape memory effect. A measurement of the circumferential strain during thermal tightening is also made for each diameter expansion method. After that, it is attempted to identify the axial push-out strength and bending strength of the joints by measuring strain during the diameter expansion and thermal tightening processes. The results demonstrate that both the axial push-out strength and bending strength of pipe joints can be predicted in prior to the installation through the measured strain during the diameter expansion and heating processes.

Lithofacies and Diagenetic Controls on Tight Silty and Sandy Upper Triassic Reservoirs of the Heshui Oil Field (Ordos Basin, North China)

Summary Tight oil, present in reservoirs of low porosity and permeability, can be regarded as a kind of unconventional resource. The tightening process in this kind of reservoir is controlled by the lithology and diagenetic history of the host formation. Upper Triassic Yanchang Formation siltstones and sandstones are the main reservoirs for hydrocarbon accumulation in the Heshui Oil Field (HOF), southwestern Ordos Basin. The reservoirs exhibit low porosity, low permeability, and strong heterogeneity. In recent years, numerous drillcores have been recovered from these units, but the porosity-permeability characteristics and burial history of these silty and sandy reservoirs have not yet been reported in detail. In this study, an integrated analysis of the lithofacies, diagenesis, and reservoir characteristics of the siltstones and sandstones was achieved using a combination of core and thin section, grain size, scanning electron microscopy (SEM), X-ray diffraction (XRD), δ13C and δ18O, mercury intrusion capillary pressure (MICP), and porosity and permeability data. Our primary goals were to quantify the porosity-permeability characteristics of these silty and sandy reservoirs, restore their diagenetic histories, and examine the paragenetic relationship of reservoir tightness to hydrocarbon accumulation. The silty and sandy reservoirs represent braided river delta facies consisting of compositionally and texturally immature sediments. In the burial environment, they underwent complex diagenetic processes that reduced porosity from an initial average of ~38% to the present ~8%. Porosity-destructive processes included compaction (~ –12.5%) and cementation (~ –21%), with increases in porosity related to grain dissolution (~ +2.2%) and tectonic fractures (~ +1.1%). The reservoirs underwent four diagenetic stages: (1) Penesyngenetic and Eogenetic A Stage (Late Triassic-Early Jurassic); (2) Eogenetic B Stage (Late Jurassic); (3) Early Mesogenetic A Stage (Early Cretaceous); and (4) Late Mesogenetic A Stage (Late Cretaceous to recent). Hydrocarbon charging of these reservoirs occurred in three pulses. Existing pore space was partly filled by hydrocarbons during the Eogenetic B Stage. A second hydrocarbon charging event occurred during the Early Mesogenetic A Stage, when residual primary intergranular pores and secondary dissolution pores were filled. A third hydrocarbon charging event occurred during the Late Mesogenetic A Stage, when the reservoirs were tight. Siltstone beds deposited in delta front environments are the main future exploration targets in the Chang 6 to 8 members. The results of this study provide a useful reference framework for future exploration of hydrocarbon resources in the Upper Triassic Yanchang Formation of the HOF, as well as potential insights into the evolution of similarly tight reservoirs in other basins.

Fastening reliability analysis of bolted joint anti-self-loosening

In the absence of external forces, the preload of the bolted joint will decrease due to self-loosening after the tightening process is completed. Self-loosening of a bolted joint will result in unstable contact between connected components, affecting the overall performance of mechanical equipment. This paper proposes a method for fastening reliability analysis of bolted joints considering the uncertainty of preload, friction coefficients, and material properties. The finite element method (FEM) is used to study the self-loosening behavior of a bolted joint under elastic conditions. The metamodel is constructed based on the proposed finite element model to improve computational efficiency. In addition, the fastening reliability of the bolted joint is calculated using the Monte Carlo simulation (MCS) method. Finally, the practical application of calculating the fastening reliability and a detailed analysis is presented to evaluate the proposed method's efficiency. The results show that the recovery of accumulated elastic deformation of a bolted joint generates self-loosening. In contrast, the torsional elastic deformation of the bolt rod causes relative rotation between the bolt and the nut. When the characteristic parameters obey the normal distribution, the probability distribution of preload reduction ratio approximately obeys the normal distribution. According to the proposed reliability calculation method, the reliability of bolted joint self-loosening is 99.7725% when the preload reduction ratio exceeding 0.026 is considered as self-loosening failure.

Unsupervised anomaly detection in unbalanced time series data from screw driving processes using k-means clustering

Since bolted joints are ubiquitous in manufacturing, their effective and reliable quality assurance is particularly important. Most tightening processes rely on statistical methods to detect faulty screw connections already during assembly. In this paper, we address the detection of faulty tightening processes using a clustering based approach from the field of Unsupervised Machine Learning. In particular, we deploy the k-Means algorithm on a real-world dataset from the automotive industry. The model uses Dynamic Time Warping to determine the similarity between the normal and abnormal tightening processes, treating each one as an independent temporal sequence. This approach offers three advantages compared to existing supervised methods: 1.) time series with different lengths can be utilized without extensive preprocessing steps, 2.) errors never seen before can be detected using the unsupervised approach, and 3.) extensive manual efforts to generate labels are no longer necessary. To evaluate the approach, it is applied in a scenario where actual class labels are available. This allows evaluating the clustering results using traditional classification scores. The approach manages to achieve an accuracy of up to 88.89% and a macro-average F1-score of up to 63.65%.

Mechanical tightening of a synthetic molecular knot

<h2>Summary</h2> Little is known regarding the effects of knotting on the mechanical properties of individual molecules. Here, we report on the force response of discrete synthetic small-molecule trefoil knots upon tightening. By combining single-molecule force spectroscopy with quantum chemical calculations, we provide evidence for the mechanism of tightening. It is associated with a higher resisting force than for larger protein knots and is modulated by the chemical environment. The central metal coordination plays a crucial role in the tightening process, as well as in the reverse process that recovers the initial knotted conformation. As a result of the compact structure, the recovery of conformation after mechanical perturbation is very fast. The tightening also plays an important role in accommodating mechanical stress. It provides a reserve of extensibility; the extra energy that the knotted strand can absorb in comparison with an unknotted strand is ∼13 kcal mol⁻¹.

Cerclage performance analysis – a biomechanical comparison of different techniques and materials

BackgroundWire cerclages play a fundamental role in fracture fixation. With an increasing variety of designs being commercially available the question arises which cerclage should be used.This study investigates the biomechanical properties of metallic and non-metallic cerclages and their different application-types. Furthermore, potential influence of muscular interposition between bone and cerclage constructs was tested.MethodsSamples of the following four different cerclage types were tested on 3D printed models of human humeri as well as on human cadaveric humeri with and without muscular interposition:Titanium Cable Cerclage (CC), Steel Wire Cerclage (SWC), Suture Tape (ST), Suture Tape Cerclage (STC) with both single- (sSTC) and double-loop application (dSTC). A preinstalled self-locking mechanism secured by the provided tensioner in the STCs being the main difference to the STs.Cyclic loading was performed to 1 kN and then linearly to a maximum load of 3 kN.Statistical analysis was performed using either one-way ANOVA and post-hoc Tukey or Kruskal–Wallis and post-hoc Dunn test depending on normalization of data (p < 0.05).ResultsWhilst all cerclage options could withstand high loads during failure testing, only within the CC and dSTC group, all samples reached the maximal testing load of 3000 N without any failure. The SWC reached 2977.5 ± 63.6 N, the ST 1970.8 ± 145.9 N, and the sSTC 1617.0 ± 341.6 N on average.Neither muscular interposition nor bone quality showed to have a negative influence on the biomechanical properties of the cerclage constructs, presenting no significant differences.ConclusionAll tested cerclage constructs produce reliable stability but differ in their resulting compression forces, in a simplified fracture model. Therefore, non-metallic cerclage alternatives can provide similar stability with less compression and stiffness to metallic cable constructs, but they may offer several advantages and could possibly provide future benefits. Especially, by offering more elasticity without losing overall stability, may offer a biologic benefit. Installing any cerclage constructs should be performed carefully, especially if poor bone quality is present, as the tightening process leads to high forces on the construct.

Torsional and compressive properties of bolted joint under forward-reverse tightening

Obtaining the stress evolution law of bolted joint during the assembly process is of great significance for tightening process design and improving assembly performance. In this study, the bolt tightening analytical model is used to obtain the deformation coordination mechanism. Then, the evolution law of the stress during assembly process are obtained by FEA model, and the influence of different assembly parameters on the stress change is analyzed. Finally, the bolt tightening experiment is carried out, which verified the theoretical hypothesis and the FEA model. The results show that: in addition to the tensile normal stress, the thread torque also generates torsional shear stress that causes the torsional deformation of the screw during the tightening process. The torsional shear stress can be reduced by forward-reverse tightening process. Meanwhile, the utilization rate of bolted joint can be improved. This can increase the assembly design margin and improve the assembly performance.

Research on Process Planning Method of Aerospace Engine Bolt Tightening Based on Digital Twin

Aerospace engine is the source of power for the development of national defense and aerospace. Engine bolt tightening is an important part of the aerospace engine production process. At present, most of the bolt tightening methods of aerospace engines are manual tightening or traditional rigid tightening, which lead to the problem of low efficiency and large engine deformation. This paper proposes a process planning method for bolt tightening of aerospace engine based on digital twin, including flexible tightening mechanism design, tightening sequence optimization, the establishment of the digital twin system of the tightening mechanism, etc. The flexible tightening mechanism is suitable for different types of aerospace engines. Based on bolt tightening sequence optimization, the deformation and stress of the cabin section during the tightening process are reduced. The bolt tightening work is completed in the digital twin system, the real-time communication of physical and digital space synchronizes the operations of them. After tightening, the residual pre-tightening force of bolts are detected based on the ultrasonic method. The results show that the proposed method can solve the problems of low efficiency of aerospace engine bolt tightening and the problem of the cabin’s large deformation. Furthermore, it provides technical reference and theoretical basis for the bolt tightening technology of aerospace engine.

Semi-Physical Simulation Optimization Method for Bolt Tightening Process Based on Reinforcement Learning

Bolted connections are the main method of connecting the components of an aero-engine low pressure rotor. Due to the influence of the elastic interaction relationship, it is easy to cause uneven distribution of the preload force of the bolt group, although it can meet the stiffness needs; however, it may lead to the deflection of the spatial relative position of the components, which is can easily cause coaxiality overrun. In view of the contradictory problem of optimization between coaxiality and stiffness of rotor assembly, this paper proposes a semi-physical simulation optimization method for the bolt tightening process based on reinforcement learning. Firstly, by studying the elastic interaction mechanism between the bolts, the elastic interaction matrix was established using finite element simulation data. On this basis, a coaxiality prediction model for the bolt tightening process was established using a GRU (gate recurrent unit) network to realize the prediction of coaxiality in the bolt tightening process. Then, through the analysis of the bolt connection stiffness, a stiffness calculation model containing the bolt stiffness, the stiffness of the connected parts, and the contact stiffness of the joint surface in series was constructed to realize the calculation of the stiffness during the bolt tightening process. Finally, with the bolt preload force as the optimization variable, coaxiality and stiffness as the optimization target, and the tightening torque and preload force of the installed bolts in the actual assembly process as the constraints, a semi-physical simulation optimization model of the bolt tightening process was established using reinforcement learning to realize the optimization of the bolt tightening process. Moreover, through the semi-physical simulation optimization method, the bolt tightening process can be installed and adjusted at the same time.

An Innovative Formulation Tightening Approach for Job-Shop Scheduling

Job shops are an important production environment for low-volume high-variety manufacturing. Its scheduling has recently been formulated as an integer linear programming (ILP) problem to take advantages of popular mixed-integer linear programming (MILP) methods, e.g., branch-and-cut. When considering a large number of parts, MILP methods may experience difficulties. To address this, a critical but much overlooked issue is formulation tightening. The idea is that if problem constraints can be transformed to directly delineate the problem convex hull in the data preprocessing stage, then a solution can be obtained by using linear programming (LP) methods without combinatorial difficulties. The tightening process, however, is fundamentally challenging because of the existence of integer variables. In this article, an innovative and systematic approach is established for the first time to tighten the formulations of individual parts, each with multiple operations, in the data preprocessing stage. It is a major advancement of our previous work on problems with binary and continuous variables to integer variables. The idea is to first link integer variables to binary variables by innovatively combining constraints so that the integer variables are uniquely determined by the binary variables. With binary and continuous variables only, it is proved that the vertices of the convex hull can be obtained based on vertices of the LP problem after relaxing binary requirements. These vertices are then converted to tightened constraints for general use. This approach significantly improves our previous results on tightening individual operations. Numerical results demonstrate significant benefits on solution quality and computational efficiency. This approach also applies to other complex ILP and MILP problems with similar characteristics and fundamentally changes the way how such problems are formulated and solved. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Scheduling is an important but difficult problem in planning and operation of job shops. The problem has been recently formulated in an integer linear programming (ILP) form to take advantage of popular mixed-integer linear programming methods. Given an ILP problem, there must exist a linear programming (LP) formulation so that all of its vertices are also the vertices to the ILP problem. If such an LP problem can be found in the data preprocessing stage, then the corresponding ILP problem is tight and can be solved by using an LP method without difficulties. In this article, an innovative and systematic approach is established to tighten the formulations of individual parts, each with one or multiple operations. It is a major advancement of our previous work on problems with binary and continuous variables by novel exploitation of the relationship between integer and binary variables in job-shop scheduling. The resulting tightened constraints are characterized by part parameters and the length of the scheduling horizon and can be easily adjusted for other data sets. Results demonstrate significant benefits on solution quality and computational efficiency. This approach also applies to other complex ILP and MILP problems with similar characteristics and fundamentally changes the way how such problems are formulated and solved.